Method and device for transmitting control information

ABSTRACT

A method for transmitting uplink control information and to an apparatus therefor. The method includes: selecting one uplink control channel resource corresponding to a plurality of HARQ-ACKs from among a plurality of uplink control channel resources; and transmitting a bit value corresponding to the plurality of HARQ-ACKs using the selected uplink control channel resource.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/808,407, filed on Jul. 24, 2015, now U.S. Pat. No. 9,642,160, whichis a continuation of U.S. patent application Ser. No. 13/821,967, filedon Mar. 8, 2013, now U.S. Pat. No. 9,161,349, which is the NationalStage filing under 35 U.S.C. 371 of International Application No.PCT/KR2011/006771, filed on Sep. 14, 2011, which claims the benefit ofU.S. Provisional Application Nos. 61/382,455, filed on Sep. 13, 2010,61/389,694, filed on Oct. 4, 2010, 61/393,366, filed on Oct. 15, 2010,61/409,957, filed on Nov. 3, 2010, and 61/422,653, filed on Dec. 13,2010, the contents of which are all hereby incorporated by referenceherein in their entirety.

TECHNICAL FIELD

The present invention relates to a wireless communication system, andmore particularly, to a method and apparatus for transmitting controlinformation.

BACKGROUND ART

Wireless communication systems have been widely deployed to providevarious types of communication services including voice and dataservices. In general, a wireless communication system is a multipleaccess system that supports communication among multiple users bysharing available system resources (e.g. bandwidth, transmit power,etc.) among the multiple users. The multiple access system may adopt amultiple access scheme such as Code Division Multiple Access (CDMA),Frequency Division Multiple Access (FDMA), Time Division Multiple Access(TDMA), Orthogonal Frequency Division Multiple Access (OFDMA), or SingleCarrier Frequency Division Multiple Access (SC-FDMA).

DISCLOSURE Technical Problem

An object of the present invention devised to solve the problem lies ina method of efficiently transmitting uplink control information and anapparatus therefor in a wireless communication system. Another object ofthe present invention is to provide a method of efficiently transmittingcontrol information, preferably, ACK/NACK information in a multicarriersituation and an apparatus therefor.

It will be appreciated by persons skilled in the art that the objectsthat could be achieved with the present invention are not limited towhat has been particularly described hereinabove and the above and otherobjects that the present invention can achieve will be more clearlyunderstood from the following detailed description taken in conjunctionwith the accompanying drawings.

Technical Solution

The object of the present invention can be achieved by providing amethod for transmitting uplink control information when a plurality ofcells including a primary cell and a secondary cell are configured in awireless communication system, the method including: selecting one PUCCH(Physical Uplink Control Channel) resource pair corresponding to aplurality of HARQ-ACKs from among a plurality of PUCCH resource pairsfor PUCCH format 1b; and transmitting a bit value corresponding to theplurality of HARQ-ACKs using the selected PUCCH resource pair throughmultiple antennas, wherein the plurality of PUCCH resource pairsincludes resources shown in the following table,

PUCCH resource pair #1 PUCCH resource pair #2 TX #N IMP_(P) EXP₁ TX #MIMP_(P+1) EXP₂wherein TX #N and TX #M respectively denote antenna ports N and M,IMP_(P) denotes a PUCCH resource linked to a lowest CCE (Control ChannelElement) index n_(CCE,P) corresponding to a PDCCH (Physical DownlinkControl Channel) relating to a PDSCH (Physical Downlink Shared Channel)in the primary cell, IMP_(P+1) represents a PUCCH resource linked ton_(CCE,P)+1, and EXP₁ and EXP₂ represent PUCCH resources configured by ahigher layer.

In another aspect of the present invention, provided herein is acommunication apparatus configured to transmit uplink controlinformation when a plurality of cells including a primary cell and asecondary cell are configured in a wireless communication system, thecommunication apparatus including an RF unit, and a processor, whereinthe processor is configured to select one PUCCH resource paircorresponding to a plurality of HARQ-ACKs from among a plurality ofPUCCH resource pairs for PUCCH format 1b and to transmit a bit valuecorresponding to the plurality of HARQ-ACKs using the selected PUCCHresource pair through multiple antennas, wherein the plurality of PUCCHresource pairs includes resources shown in the following table,

PUCCH resource pair #1 PUCCH resource pair #2 TX #N IMP_(P) EXP₁ TX #MIMP_(P+1) EXP₂wherein TX #N and TX #M respectively denote antenna ports N and M,IMP_(P) denotes a PUCCH resource linked to a lowest CCE index n_(CCE,P)corresponding to a PDCCH relating to a PDSCH in the primary cell,IMP_(P+1) represents a PUCCH resource linked to n_(CCE,P+)1, and EXP₁and EXP₂ represent PUCCH resources configured by a higher layer.

The plurality of PUCCH resource pairs may include resources shown in thefollowing table,

PUCCH PUCCH PUCCH PUCCH resource resource resource resource pair #1 pair#2 pair #3 pair #4 TX #N IMP_(P) EXP₁ EXP₃ EXP₅ TX #M IMP_(P+1) EXP₂EXP₄ EXP₆wherein EXP₃ to EXP₆ represent PUCCH resources allocated using aresource indication value included in a PDCCH corresponding to a PDSCHin the secondary cell.

The plurality of PUCCH resource pairs may include resources shown in thefollowing table,

PUCCH PUCCH PUCCH PUCCH resource resource resource resource pair #1 pair#2 pair #3 pair #4 TX #N IMP_(P) EXP₁ IMP_(S) EXP₃ TX #M IMP_(P+1) EXP₂IMP_(S+1) EXP₄wherein IMP_(S) denotes a PUCCH resource linked to a lowest CCE indexn_(CCE,S) corresponding to a PDCCH relating to a PDSCH in the secondarycell, IMP_(S+1) represents a PUCCH resource linked to n_(CCE,S)+1, andEXP₃ and EXP₄ represent PUCCH resources allocated using a resourceindication value included in the PDCCH corresponding to the PDSCH in thesecondary cell.

The resource indication value may be an offset corresponding to amultiple of 2, and EXP₃ to EXP₆ may be given as follows:

-   -   EXP₃: a first reference PUCCH index configured by the higher        layer+the offset,    -   EXP₄: the first reference PUCCH index configured by the higher        layer+the offset+1,    -   EXP₅: a second reference PUCCH index configured by the higher        layer+the offset, and    -   EXP₆: the second reference PUCCH index configured by the higher        layer+the offset+1.

The resource indication value may be an offset corresponding to amultiple of 1, and EXP₃ to EXP₆ may be given as follows:

-   -   EXP₃: a first reference PUCCH index configured by the higher        layer+the offset,    -   EXP₄: the first reference PUCCH index configured by the higher        layer+the offset+1,    -   EXP₅: a second reference PUCCH index configured by the higher        layer+the offset, and    -   EXP₆: the second reference PUCCH index configured by the higher        layer+the offset+1.

The resource indication value may be an offset corresponding to amultiple of 1, and EXP₃ to EXP₆ may be given as follows:

-   -   EXP₃: a first reference PUCCH index configured by the higher        layer,    -   EXP₄: the first reference PUCCH index configured by the higher        layer+the offset,    -   EXP₅: a second reference PUCCH index configured by the higher        layer+the offset, and    -   EXP₆: the second reference PUCCH index configured by the higher        layer+the offset.

The primary cell includes a PCC (Primary Component Carrier) and thesecondary cell includes a SCC (Secondary Component Carrier).

Advantageous Effects

According to the present invention, uplink control information can beefficiently transmitted in a wireless communication system. Furthermore,control information, preferably, ACK/NACK information can be efficientlytransmitted in a multicarrier situation.

It will be appreciated by persons skilled in the art that that theeffects that could be achieved with the present invention are notlimited to what has been particularly described hereinabove and otheradvantages of the present invention will be more clearly understood fromthe following detailed description taken in conjunction with theaccompanying drawings.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention, illustrate embodiments of the inventionand together with the description serve to explain the principle of theinvention.

In the drawings:

FIG. 1 illustrates a radio frame structure;

FIG. 2 illustrates a resource grid of a downlink slot;

FIG. 3 illustrates a downlink subframe structure;

FIG. 4 illustrates an uplink subframe structure;

FIG. 5 illustrates an example of physically mapping a PUCCH format to aPUCCH region;

FIG. 6 illustrates a slot level structure of PUCCH format 2/2a/2b;

FIG. 7 illustrates a slot level structure of PUCCH format 1a/1b;

FIG. 8 illustrates an example of determining a PUCCH resource forACK/NACK;

FIG. 9 illustrates a carrier aggregation (CA) communication system;

FIG. 10 illustrates scheduling in case of aggregation of a plurality ofcarriers;

FIGS. 11, 12 and 13 illustrate PUCCH resource allocation according to anembodiment of the present invention;

FIG. 14 illustrates an ACK/NACK selection scheme according to LTE;

FIG. 15 illustrates an example of transmitting ACK/NACK according to anembodiment of the present invention; and

FIG. 16 illustrates a base station (BS) and a UE applicable to anembodiment of the present invention.

BEST MODE

Embodiments of the present invention are applicable to a variety ofwireless access technologies such as Code Division Multiple Access(CDMA), Frequency Division Multiple Access (FDMA), Time DivisionMultiple Access (TDMA), Orthogonal Frequency Division Multiple Access(OFDMA), and Single Carrier Frequency Division Multiple Access(SC-FDMA). CDMA can be implemented as a radio technology such asUniversal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA can beimplemented as a radio technology such as Global System for Mobilecommunications (GSM)/General Packet Radio Service (GPRS)/Enhanced DataRates for GSM Evolution (EDGE). OFDMA can be implemented as a radiotechnology such as Institute of Electrical and Electronics Engineers(IEEE) 802.11 (Wireless Fidelity (Wi-Fi)), IEEE 802.16 (Worldwideinteroperability for Microwave Access (WiMAX)), IEEE 802.20, EvolvedUTRA (E-UTRA). UTRA is a part of Universal Mobile TelecommunicationsSystem (UMTS). 3^(rd) Generation Partnership Project (3GPP) Long TermEvolution (LTE) is a part of Evolved UMTS (E-UMTS) using E-UTRA,employing OFDMA for downlink and SC-FDMA for uplink. LTE-Advanced(LTE-A) is an evolution of 3GPP LTE.

While the following description is given, centering on 3GPP LTE/LTE-A toclarify the description, this is purely exemplary and thus should not beconstrued as limiting the present invention.

FIG. 1 illustrates a radio frame structure.

Referring to FIG. 1, a radio frame includes 10 subframes. A subframeincludes two slots in time domain. A time for transmitting one subframeis defined as a transmission time interval (TTI). For example, onesubframe may have a length of 1 millisecond (ms), and one slot may havea length of 0.5 ms. One slot includes a plurality of orthogonalfrequency division multiplexing (OFDM) or single carrier frequencydivision multiple access (SC-FDMA) symbols in time domain. Since LTEuses the OFDMA in the downlink and uses SC-FDMA in the uplink, an OFDMor SC-FDMA symbol represents one symbol period. A resource block (RB) isa resource allocation unit, and includes a plurality of contiguoussubcarriers in one slot. The structure of the radio frame is shown forexemplary purposes only. Thus, the number of subframes included in theradio frame or the number of slots included in the subframe or thenumber of OFDM symbols included in the slot may be modified in variousmanners.

FIG. 2 illustrates a resource grid of a downlink slot.

Referring to FIG. 2, a downlink slot includes a plurality of OFDMsymbols in the time domain. One downlink slot may include 7(6) OFDMsymbols, and one resource block (RB) may include 12 subcarriers in thefrequency domain. Each element on the resource grid is referred to as aresource element (RE). One RB includes 12×7(6) REs. The number N_(RB) ofRBs included in the downlink slot depends on a downlink transmitbandwidth. The structure of an uplink slot may be same as that of thedownlink slot except that OFDM symbols by replaced by SC-FDMA symbols.

FIG. 3 illustrates a downlink subframe structure.

Referring to FIG. 3, a maximum of three (four) OFDM symbols located in afront portion of a first slot within a subframe correspond to a controlregion to which a control channel is allocated. The remaining OFDMsymbols correspond to a data region to which a physical downlink sharedchancel (PDSCH) is allocated. A PDSCH is used to carry a transport block(TB) or a codeword (CW) corresponding to the TB. The TB means a datablock transmitted from a MAC layer to a PHY layer through a transportchannel. The codeword corresponds to a coded version of a TB. Thecorresponding relationship between the TB and the CW depends on swiping.In the specifically, the PDSCH, TB and CW are interchangeably used.Examples of downlink control channels used in LTE include a physicalcontrol format indicator channel (PCFICH), a physical downlink controlchannel (PDCCH), a physical hybrid ARQ indicator channel (PHICH), etc.The PCFICH is transmitted at a first OFDM symbol of a subframe andcarries information regarding the number of OFDM symbols used fortransmission of control channels within the subframe. The PHICH is aresponse of uplink transmission and carries an HARQ acknowledgment(ACK)/not-acknowledgment (NACK) signal.

Control information transmitted through the PDCCH is referred to asdownlink control information (DCI). The DCI includes resource allocationinformation for a UE or a UE group and other control information. Forexample, the DCI includes uplink/downlink scheduling information, anuplink transmit (Tx) power control command, etc. Transmission modes andinformation content of DCI formats for configuring a multi-antennatechnology are as follows.

Transmission Mode

-   -   Transmission mode 1: Transmission from a single base station        antenna port    -   Transmission mode 2: Transmit diversity    -   Transmission mode 3: Open-loop spatial multiplexing    -   Transmission mode 4: Closed-loop spatial multiplexing    -   Transmission mode 5: Multi-user MIMO    -   Transmission mode 6: Closed-loop rank-1 precoding    -   Transmission mode 7: Transmission using UE-specific reference        signals

DCI Format

-   -   Format 0: Resource grants for the PUSCH transmissions (uplink)    -   Format 1: Resource assignments for single codeword PDSCH        transmissions (transmission modes 1, 2 and 7)    -   Format 1A: Compact signaling of resource assignments for single        codeword PDSCH (all modes)    -   Format 1B: Compact resource assignments for PDSCH using rank-1        closed loop precoding (mod 6)    -   Format 1C: Very compact resource assignments for PDSCH (e.g.        paging/broadcast system information)    -   Format 1D: Compact resource assignments for PDSCH using        multi-user MIMO (mode 5)    -   Format 2: Resource assignments for PDSCH for closed-loop MIMO        operation (mode 4)    -   Format 2A: Resource assignments for PDSCH for open-loop MIMO        operation (mode 3)    -   Format 3/3A: Power control commands for PUCCH and PUSCH with        2-bit/1-bit power adjustments

As described above, the PDCCH may carry a transport format and aresource allocation of a downlink shared channel (DL-SCH), resourceallocation information of an uplink shared channel (UL-SCH), paginginformation on a paging channel (PCH), system information on the DL-SCH,information on resource allocation of an upper-layer control messagesuch as a random access response transmitted on the PDSCH, a set of Txpower control commands on individual UEs within an arbitrary UE group, aTx power control command, information on activation of a voice over IP(VoI P), etc. A plurality of PDCCHs can be transmitted within a controlregion. The UE can monitor the plurality of PDCCHs. The PDCCH istransmitted on an aggregation of one or several consecutive controlchannel elements (CCEs). The CCE is a logical allocation unit used toprovide the PDCCH with a coding rate based on a state of a radiochannel. The CCE corresponds to a plurality of resource element groups(REGs). A format of the PDCCH and the number of bits of the availablePDCCH are determined by the number of CCEs. The BS determines a PDCCHformat according to DCI to be transmitted to the UE, and attaches acyclic redundancy check (CRC) to control information. The CRC is maskedwith a unique identifier (referred to as a radio network temporaryidentifier (RNTI)) according to an owner or usage of the PDCCH. If thePDCCH is for a specific UE, a unique identifier (e.g., cell-RNTI(C-RNTI)) of the UE may be masked to the CRC. Alternatively, if thePDCCH is for a paging message, a paging identifier (e.g., paging-RNTI(P-RNTI)) may be masked to the CRC. If the PDCCH is for systeminformation (more specifically, a system information block (SIB)), asystem information RNTI (SI-RNTI) may be masked to the CRC. When thePDCCH is for a random access response, a random access-RNTI (RA-RNTI)may be masked to the CRC.

FIG. 4 illustrates an uplink subframe structure. Referring to FIG. 4, anuplink subframe includes a plurality of (e.g. 2) slots. A slot mayinclude different numbers of SC-FDMA symbols according to CP lengths.The uplink subframe is divided into a control region and a data regionin the frequency domain. The data region is allocated with a PUSCH andused to carry a data signal such as audio data. The control region isallocated a PUCCH and used to carry uplink control information (UCI).The PUCCH includes an RB pair located at both ends of the data region inthe frequency domain and hopped in a slot boundary.

The PUCCH can be used to transmit the following control information.

-   -   Scheduling Request (SR): This is information used to request a        UL-SCH resource and is transmitted using On-Off Keying (OOK)        scheme.    -   HARQ ACK/NACK: This is a response signal to a downlink data        packet on a PDSCH and indicates whether the downlink data packet        has been successfully received. A 1-bit ACK/NACK signal is        transmitted as a response to a single downlink codeword and a        2-bit ACK/NACK signal is transmitted as a response to two        downlink codewords.    -   Channel Quality Indicator (CQI): This is feedback information        about a downlink channel. Feedback information regarding        Multiple Input Multiple Output (MIMO) includes Rank Indicator        (RI) and Precoding Matrix Indicator (PMI). 20 bits are used for        each subframe.

The quantity of control information (UCI) that a UE can transmit througha subframe depends on the number of SC-FDMA symbols available forcontrol information transmission. The SC-FDMA symbols available forcontrol information transmission correspond to SC-FDMA symbols otherthan SC-FDMA symbols of the subframe, which are used for referencesignal transmission. In the case of a subframe in which a SoundingReference Signal (SRS) is configured, the last SC-FDMA symbol of thesubframe is excluded from the SC-FDMA symbols available for controlinformation transmission. A reference signal is used to detect coherenceof the PUCCH. The PUCCH supports 7 formats according to informationtransmitted thereon.

Table 1 shows the mapping relationship between PUCCH formats and UCI inLTE.

TABLE 1 PUCCH format UCI (Uplink Control Information) Format 1 SR(Scheduling Request) (non-modulated waveform Format 1a 1-bit HARQACK/NACK (SR exist/non-exist) Format 1b 2-bit HARQ ACK/NACK (SRexist/non-exist) Format 2 CQI (20 coded bits) Format 2 CQI and 1- or2-bit HARQ ACK/NACK (20 bits) (corresponding to only extended CP) Format2a CQI and 1-bit HARQ ACK/NACK (20 + 1 coded bits) Format 2b CQI and2-bit HARQ ACK/NACK (20 + 2 coded bits)

FIG. 5 illustrates an example of physically mapping a PUCCH format to aPUCCH region.

Referring to FIG. 5, PUCCH formats are mapped onto RBs in the order ofPUCCH formats 2/2a/2b (CQI) (e.g. PUCCH regions m=0, 1), PUCCH formats2/2a/2b (CQI) or PUCCH formats 1/1a/1b (SR/HARQ ACK/NACK) (e.g. PUCCHregion m=2 if present), and PUCCH formats 1/1a/1b (SR/HARQ ACK/NACK)(e.g. PUCCH regions m=3, 4, 5), starting from the band-edge, andtransmitted. The number of PUCCH RBs, N_(RB) ⁽²⁾, which can be used forPUCCH formats 2/2a/2b (CQI) is signaled to a UE in a cell throughbroadcast signaling.

The periodicity and frequency resolution to be used by a UE to reportCQI are both controlled by the BS. In the time domain, both periodic andaperiodic CQI reporting are supported. The PUCCH format 2 is used forperiodic CQI reporting. In periodic CQI reporting, CQI is piggybacked ondata and then transmitted through a PUSCH if the PUSCH is scheduled fora subframe reserved for CQI transmission. A PUSCH is used for aperiodicCQI reporting, whereby the BS specifically instructs the UE to send anindividual CQI report embedded into a resource which is scheduled foruplink data transmission.

FIG. 6 illustrates a slot level structure of PUCCH formats 2/2a/2b. ThePUCCH formats 2/2a/2b are used for CQI transmission. In the case ofnormal CP, SC-FDMA symbols #1 and #5 in a slot are used for transmissionof a Demodulation Reference Signal (DM RS). In the case of extended CP,only SC-FDMA #3 in the slot is used for DM RS transmission.

Referring to FIG. 6, at a subframe level, 10-bit CSI is channel-codedinto 20 coded bits using (20, k) Reed-Muller code punctured at a rate of1/2 (not shown). The coded bits are scrambled (not shown) and thenmapped to Quadrature Phase Shift Keying (QPSK) constellation (QPSKmodulation). Scrambling can be performed using length-31 gold sequencein a similar manner that PUSCH data is scrambled. 10 QPSK modulationsymbols are generated according to the QPSK modulation, and 5 QPSKmodulation symbols d₀, d₁, d₂, d₃ and d₄ are transmitted through SC-FDMAsymbols corresponding thereto in each slot. Each of the QPSK modulationsymbols is used to modulate a length-12 base RS sequence r_(u,0) priorto being subjected to Inverse Fast Fourier Transform (IFFT).Consequently, the RS sequence is cyclic-shifted in the time domainaccording to the QPSK modulation symbol value (d_(x)*r_(u,0) ^((αx)),x=0 to 4). The RS sequence multiplied by the QPSK modulation symbol iscyclic-shifted (α_(cs,x), x=1, 5). When the number of cyclic shifts isN, N UEs can be multiplexed on the same CSI PUCCH RB. While a DM RSsequence is similar to a CSI sequence in the frequency domain, the DM RSsequence is not modulated by a CQI modulation symbol.

Parameters/resources for periodic CQI reports are configuredsemi-statically according to higher layer (e.g. Radio Resource Control(RRC)) signaling. If PUCCH resource index n_(PUCCH) ⁽²⁾ is set for CQItransmission, for example, CQI is periodically transmitted on a CQIPUCCH linked to PUCCH resource index n_(PUCCH) ⁽²⁾. PUCCH resource indexn_(PUCCH) ⁽²⁾ indicates a PUCCH RB and cyclic shift α_(cs).

FIG. 7 illustrates a slot level structure of PUCCH formats 1a/1b. ThePUCCH formats 1a/1b are used for ACK/NACK transmission. In the case ofnormal CP, SC-FDMA symbols #2, #3 and #4 are used for DM RStransmission. In the case of extended CP, SC-FDMA symbols #2 and #3 areused for DM RS transmission. Accordingly, 4 SC-FDMA symbols in a slotare used for ACK/NACK transmission. PUCCH format 1a/1b is called PUCCHformat 1 for convenience.

Referring to FIG. 7, 1-bit [b(0)] and 2-bit [b(0)b(1)] ACK/NACKinformation are modulated according to BPSK and QPSK modulation schemesrespectively, to generate one ACK/NACK modulation symbol d₀. Each bit[b(i), i=0, 1] of the ACK/NACK information indicates a HARQ response toa corresponding DL transport block, corresponds to 1 in the case ofpositive ACK and corresponds to 0 in case of negative ACK (NACK). Table2 shows a modulation table defined for PUCCH formats 1a and 1b in LTE.

TABLE 2 PUCCH format b(0), . . . , b(M_(bit) − 1) d(0) 1a 0   1 1 −1 1b00   1 01 −j 10   j 11 −1

PUCCH formats 1a/1b perform time domain spreading using an orthogonalspreading code W₀, W₁, W₂, W₃, (e.g. Walsh-Hadamard or DFT code) inaddition to cyclic shift α_(cs,x) in the frequency domain. In the caseof PUCCH formats 1a/1b, a larger number of UEs can be multiplexed on thesame PUCCH RB because code multiplexing is used in both frequency andtime domains.

RSs transmitted from different UEs are multiplexed using the same methodas is used to multiplex UCI. The number of cyclic shifts supported bySC-FDMA symbols for PUCCH ACK/NACK RB can be configured by cell-specifichigher layer signaling parameter Δ_(shift) ^(PUCCH). Δ_(shift)^(PUCCH)ϵ{1, 2, 3} represents that shift values are 12, 6 and 4,respectively. In time-domain CDM, the number of spreading codes actuallyused for ACK/NACK can be limited by the number of RS symbols becausemultiplexing capacity of RS symbols is less than that of UCI symbols dueto a smaller number of RS symbols.

FIG. 8 illustrates an example of determining PUCCH resources forACK/NACK. In LTE, a plurality of PUCCH resources for ACK/NACK are sharedby a plurality of UEs in a cell every time the UEs need the PUCCHresources rather than allocated to UEs in advance. Specifically, a PUCCHresource used by a UE to transmit an ACK/NACK signal corresponds to aPDCCH on which scheduling information on DL data involving the ACK/NACKsignal is delivered. The region in which the PDCCH is transmitted in aDL subframe is configured with a plurality of Control Channel Elements(CCEs), and the PDCCH transmitted to the UE is composed of one or moreCCEs. The UE transmits the ACK/NACK signal through a PUCCH resourcecorresponding to a specific one (e.g. first CCE) of the CCEsconstituting the received PDCCH.

Referring to FIG. 8, each block in a Downlink Component Carrier (DL CC)represents a CCE and each block in an Uplink Component Carrier (UL CC)indicates a PUCCH resource. Each PUCCH index corresponds to a PUCCHresource for an ACK/NACK signal. If information on a PDSCH is deliveredon a PDCCH composed of CCEs #4, #5 and #6, as shown in FIG. 8, a UEtransmits an ACK/NACK signal on PUCCH #4 corresponding to CCE #4, thefirst CCE of the PDCCH. FIG. 8 illustrates a case in which maximum MPUCCHs are present in the UL CC when maximum N CCEs exist in the DL CC.Though N can equal M, N may differ from M and CCEs are mapped to PUCCHsin an overlapped manner.

Specifically, a PUCCH resource index in LTE is determined as follows.n ⁽¹⁾ _(PUCCH) =n _(CCE) +N ⁽¹⁾ _(PUCCH)  [Equation 1]

Here, n⁽¹⁾ _(PUCCH) represents a resource index of PUCCH format 1 forACK/NACK/DTX transmission, N⁽¹⁾ _(PUCCH) denotes a signaling valuereceived from a higher layer, and n_(CCE) denotes the smallest value ofCCE indexes used for PDCCH transmission. A cyclic shift, an orthogonalspreading code and a Physical Resource Block (PRB) for PUCCH formats1a/1b are obtained from n⁽¹⁾ _(PUCCH).

When an LTE system operates in TDD, a UE transmits one multiplexedACK/NACK signal for a plurality of PDSCHs received through subframes atdifferent timings. Specifically, the UE transmits one multiplexedACK/NACK signal for a plurality of PDSCHs using an ACK/NACK channelselection scheme (PUCCH selection scheme). The ACK/NACK channelselection scheme is also referred to as a PUCCH selection scheme. Whenthe UE receives a plurality of DL data in the ACK/NACK channel selectionscheme, the UE occupies a plurality of UL physical channels in order totransmit a multiplexed ACK/NACK signal. For example, when the UEreceives a plurality of PDSCHs, the UE can occupy the same number ofPUCCHs as the PDSCHs using a specific CCE of a PDCCH which indicateseach PDSCH. In this case, the UE can transmit a multiplexed ACK/NACKsignal using combination of which one of the occupied PUCCHs is selectedand modulated/coded results applied to the selected PUCCH.

Table 3 shows an ACK/NACK channel selection scheme defined in LTE.

TABLE 3 HARQ-ACK(0), HARQ-ACK(1), Subframe HARQ-ACK(2), HARQ-ACK(3) n⁽¹⁾_(PUCCH, X) b(0), b(1) ACK, ACK, ACK, ACK n⁽¹⁾ _(PUCCH, 1) 1, 1 ACK,ACK, ACK, NACK/DTX n⁽¹⁾ _(PUCCH, 1) 1, 0 NACK/DTX, NACK/DTX, NACK, DTXn⁽¹⁾ _(PUCCH, 2) 1, 1 ACK, ACK, NACK/DTX, ACK n⁽¹⁾ _(PUCCH, 1) 1, 0NACK, DTX, DTX, DTX n⁽¹⁾ _(PUCCH, 0) 1, 0 ACK, ACK, NACK/DTX, NACK/DTXn⁽¹⁾ _(PUCCH, 1) 1, 0 ACK, NACK/DTX, ACK, ACK n⁽¹⁾ _(PUCCH, 3) 0, 1NACK/DTX, NACK/DTX, NACK/DTX, n⁽¹⁾ _(PUCCH, 3) 1, 1 NACK ACK, NACK/DTX,ACK, NACK/DTX n⁽¹⁾ _(PUCCH, 2) 0, 1 ACK, NACK/DTX, NACK/DTX, ACK n⁽¹⁾_(PUCCH, 0) 0, 1 ACK, NACK/DTX, NACK/DTX, NACK/DTX n⁽¹⁾ _(PUCCH, 0) 1, 1NACK/DTX, ACK, ACK, ACK n⁽¹⁾ _(PUCCH, 3) 0, 1 NACK/DTX, NACK, DTX, DTXn⁽¹⁾ _(PUCCH, 1) 0, 0 NACK/DTX, ACK, ACK, NACK/DTX n⁽¹⁾ _(PUCCH, 2) 1, 0NACK/DTX, ACK, NACK/DTX, ACK n⁽¹⁾ _(PUCCH, 3) 1, 0 NACK/DTX, ACK,NACK/DTX, NACK/DTX n⁽¹⁾ _(PUCCH, 1) 0, 1 NACK/DTX, NACK/DTX, ACK, ACKn⁽¹⁾ _(PUCCH, 3) 0, 1 NACK/DTX, NACK/DTX, ACK, NACK/DTX n⁽¹⁾ _(PUCCH, 2)0, 0 NACK/DTX, NACK/DTX, NACK/DTX, ACK n⁽¹⁾ _(PUCCH, 3) 0, 0 DTX, DTX,DTX, DTX N/A N/A

In Table 3, HARQ-ACK(i) indicates the HARQ ACK/NACK/DTX result of ani-th data unit (0≤i≤3). DTX (Discontinuous Transmission) represents thatthere is no transmission of a data unit corresponding to HARQ-ACK(i) orthe UE does not detect the data unit corresponding to HARQ-ACK(i).Maximum 4 PUCCH resources (i.e., n⁽¹⁾ _(PUCCH,0) to n⁽¹⁾ _(PUCCH,3)) canbe occupied for each data unit. The multiplexed ACK/NACK signal istransmitted through one PUCCH resource selected from the occupied PUCCHresources. In Table 3, n⁽¹⁾ _(PUCCH,X) represents a PUCCH resourceactually used for ACK/NACK transmission, and b(0)b(1) indicates two bitstransmitted through the selected PUCCH resource, which are modulatedusing QPSK. For example, when the UE has decoded 4 data unitssuccessfully, the UE transits bits (1, 1) to a BS through a PUCCHresource linked with n⁽¹⁾ _(PUCCH,1). Since combinations of PUCCHresources and QPSK symbols cannot represent all available ACK/NACKsuppositions, NACK and DTX are coupled except in some cases (NACK/DTX,N/D).

FIG. 9 illustrates a Carrier Aggregation (CA) communication system. Touse a wider frequency band, an LTE-A system employs CA (or bandwidthaggregation) technology which aggregates a plurality of UL/DL frequencyblocks to obtain a wider UL/DL bandwidth. Each frequency block istransmitted using a Component Carrier (CC). The CC can be regarded as acarrier frequency (or center carrier, center frequency) for thefrequency block.

Referring to FIG. 9, a plurality of UL/DL CCs can be aggregated tosupport a wider UL/DL bandwidth. The CCs may be contiguous ornon-contiguous in the frequency domain. Bandwidths of the CCs can beindependently determined. Asymmetrical CA in which the number of UL CCsis different from the number of DL CCs can be implemented. For example,when there are two DL CCs and one UL CC, the DL CCs can correspond tothe UL CC in the ratio of 2:1. A DL CC/UL CC link can be fixed orsemi-statically configured in the system. Even if the system bandwidthis configured with N CCs, a frequency band that a specific UE canmonitor/receive can be limited to M (<N) CCs. Various parameters withrespect to CA can be set cell-specifically, UE-group-specifically, orUE-specifically. Control information may be transmitted/received onlythrough a specific CC. This specific CC can be referred to as a PrimaryCC (PCC) (or anchor CC) and other CCs can be referred to as SecondaryCCs (SCCs).

In LTE-A, the concept of a cell is used to manage radio resources. Acell is defined as a combination of downlink resources and uplinkresources. Yet, the uplink resources are not mandatory. Therefore, acell may be composed of downlink resources only or both downlinkresources and uplink resources. The linkage between the carrierfrequencies (or DL CCs) of downlink resources and the carrierfrequencies (or UL CCs) of uplink resources may be indicated by systeminformation. A cell operating in primary frequency resources (or a PCC)may be referred to as a primary cell (PCell) and a cell operating insecondary frequency resources (or an SCC) may be referred to as asecondary cell (SCell). The PCell is used for a UE to establish aninitial connection or re-establish a connection. The PCell may refer toa cell indicated during handover. The SCell may be configured after anRRC connection is established and may be used to provide additionalradio resources. The PCell and the SCell may collectively be referred toas a serving cell. Accordingly, a single serving cell composed of aPCell only exists for a UE in an RRC_Connected state, for which CA isnot configured or which does not support CA. On the other hand, one ormore serving cells exist, including a PCell and entire SCells, for a UEin an RRC_CONNECTED state, for which CA is configured. For CA, a networkmay configure one or more SCells in addition to an initially configuredPCell, for a UE supporting CA during connection setup after an initialsecurity activation operation is initiated.

FIG. 10 illustrates scheduling when a plurality of carriers isaggregated. It is assumed that 3 DL CCs are aggregated and DL CC A isconfigured as a PDCCH CC. DL CC A, DL CC B and DL CC C can be calledserving CCs, serving carriers, serving cells, etc. If CIF is disabled, aDL CC can transmit only a PDCCH that schedules a PDSCH corresponding tothe DL CC without a CIF. When the CIF is enabled according toUE-specific (or UE-group-specific or cell-specific) higher layersignaling, DL CC A (monitoring DL CC) can transmit not only a PDCCH thatschedules the PDSCH corresponding to the DL CC A but also PDCCHs thatschedule PDSCHs of other DL CCs. In this case, DL CC B and DL CC C thatare not configured as PDCCH CCs do not deliver PDCCHs. Accordingly, theDL CC A (PDCCH CC) needs to include all of a PDCCH search space relatingto the DL CC A, a PDCCH search space relating to the DL CC B and a PDCCHsearch space relating to the DL CC C.

LTE-A considers transmission of a plurality of ACK/NACKinformation/signals with respect to a plurality of PDSCHs, which aretransmitted through a plurality of DL CCs, through a specific UL CC(e.g. UL PCC or UL PCell). For description, it is assumed that a UEoperates in a SU-MIMO (Single User-Multiple Input Multiple Output) modein a certain DL CC to receive 2 codewords (or transport blocks). In thiscase, the UE needs to be able to transmit 4 feedback states, ACK/ACK,ACK/NACK, NACK/ACK and NACK/NACK, or up to 5 feedback states includingeven DTX for the DL CC. If the DL CC is configured to support a singlecodeword (or transport block), up to 3 states of ACK, NACK and DTX arepresent for the DL CC. Accordingly, if NACK and DTX are processed as thesame state, a total of 2 feedback states of ACK and NACK/DTX are presentfor the DL CC. Accordingly, if the UE aggregates a maximum of 5 DL CCsand operates in the SU-MIMO mode in all CCs, the UE can have up to 55transmittable feedback states and an ACK/NACK payload size forrepresenting the feedback states corresponds to 12 bits. If DTX and NACKare processed as the same state, the number of feedback states is 45 andan ACK/NACK payload size for representing the same is 10 bits.

To achieve this, LTE-A considers a scheme of channel coding (e.g.Reed-Muller coding, Tail-biting convolutional coding, etc.) a pluralityof ACKs/NACKs and transmitting a plurality of ACK/NACKinformation/signals using PUCCH format 2, or a new PUCCH format (e.g.block-spread based PUCCH format). Furthermore, LTE-A discussestransmission of a plurality of ACK/NACK information/signals using PUCCHformat 1a/1b and ACK/NACK multiplexing (i.e. ACK/NACK selection) in amulti-carrier situation.

In an LTE TDD system, ACK/NACK multiplexing (i.e. ACK/NACK channelselection) is used to transmit a plurality of ACK/NACK responses withrespect to a plurality of PDSCHs transmitted through a plurality of DLsubframes, through one UL subframe. In LTE, a UE uses an implicit PUCCHresource corresponding to each PDCCH that schedules each PDSCH in orderto reserve a plurality of PUCCH resources for ACK/NACK multiplexing(hereinafter, implicit ACK/NACK selection scheme). Specifically, a PUCCHresource is linked to a lowest CCE index n_(CCE) (refer to Equation 1)corresponding to a PDCCH related to the PUCCH resource.

LTE-A considers transmission of a plurality of ACK/NACKinformation/signals for a plurality of PDSCHs transmitted through aplurality of DL CCs, through a specific UL CC. To achieve this, in thecase of a MIMO transmission mode CC (simply, MIMO CC) that can carry upto 2 codewords (CWs), 2 implicit PUCCHs #1 and #2 respectively linked toa lowest CCE index n_(CCE) of a PDCCH that schedules the correspondingCC and the following index n_(CCE)+1, or implicit PUCCH #1 and anexplicit PUCCH previously allocated through RRC may be used. In the caseof a non-MIMO transmission mode CC (simply, non-MIMO CC) that can carrya maximum of 1 codeword, an ACK/NACK selection scheme of using onlyimplicit PUCCH #1 linked to a lowest CCE index n_(CCE) of a PDCCH thatschedules the corresponding CC may be considered. In other words, whenACK/NACK transmission is performed through a single antenna (port), thetotal number of PUCCH resources for ACK/NACK selection is configured asa maximum number of CWs that can be transmitted through all CCsallocated to a UE. This condition is called “condition #1” forconvenience.

Table 4 shows an example of ACK/NACK (A/N) state-to-symbol(S) mappingfor ACK/NACK selection under condition #1 when 2 CCs (e.g. 1 MIMO CC+1non-MIMO CC) are allocated. In Table 5, the A/N state indicates aplurality of HARQ-ACK responses (e.g. HARQ-ACK(1), HARQ-ACK(2) andHARQ-ACK(3)). HARQ-ACK(1) and HARQ-ACK(2) correspond to HARQ-ACKs forthe MIMO CC and HARQ-ACK(3) corresponds to HARQ-ACK for the non-MIMO CC.In Table 4, S denotes a modulation symbol (e.g. BPSK or QPSK symbol)mapped/transmitted to/on a PUCCH resource. The number of symbols mappedto the same PUCCH resource may be varied according to the total numberof ACK/NACK states. In Table 4, S0 to S3 represent QPSK modulationsymbols (e.g. {+1, −1, +j, −j}).

MIMO CC PUCCHs #1/#2 denote PUCCH resources (indexes) linked to the MIMOCC. For example, MIMO CC PUCCHs #1/#2 include PUCCH resources (indexes)linked to a PDCCH corresponding to a PDSCH on the MIMO CC. Non-MIMO CCPUCCH #1 indicates a PUCCH resource (index) linked to the non-MIMO CC.For example, non-MIMO CC PUCCH #1 includes a PUCCH resource (index)linked to a PDCCH corresponding to a PDSCH on the non-MIMO CC.

TABLE 4 MIMO CC MIMO CC non-MIMO CC A/N state PUCCH #1 PUCCH #2 PUCCH #1State #0 S0 0 0 State #1 S1 0 0 State #2 S2 0 0 State #3 S3 0 0 State #40 S0 0 State #5 0 S1 0 State #6 0 S2 0 State #7 0 S3 0 State #8 0 0 S0State #9 0 0 S1 State #10 0 0 S2 State #11 0 0 S3

In case of implicit ACK/NACK selection, an ACK/NACK state having DTX(i.e. a PDCCH that schedules a corresponding CC is not successfullyreceived/detected) information for the corresponding CC cannot be mappedto an implicit PUCCH resource linked to the PDCCH that schedules the CC(i.e. linked to the CC). This is because DTX for a certain CC means thatan implicit PUCCH resource linked to the CC is not available. That is,an implicit PUCCH resource linked to a CC and an A/N state mapped to theimplicit PUCCH resource can be used/transmitted only when a PDCCH thatschedules the CC is successfully received/detected. This is called“implicit mapping” for convenience.

LTE-A considers ACK/NACK transmission through transmit diversity (TxD).For example, SCBC (Space Code Block coding) can be considered as a TxDscheme for ACK/NACK selection. When it is assumed that 2 antennas(ports) are present, SCBC transmits a symbol S (modulation symbol towhich an ACK/NACK state is mapped) through a first PUCCH resource incase of the first antenna (port) and transmits a modified symbol S* (or−S*) obtained by applying space coding (e.g. conjugate operation) to thesymbol through a second PUCCH resource in case of the second antenna(port).

Equation 2 represents SCBC for ACK/NACK channel selection. It is assumedthat 2 antennas (ports) and 2 PUCCH resources ch1 and ch2 are presentfor convenience.

$\begin{matrix}{\begin{matrix}{{Ant}{\# 1}} \\{{Ant}{\# 2}}\end{matrix}\mspace{14mu}\overset{\begin{matrix}{{ch}\; 1} & {{ch}\; 2}\end{matrix}}{\begin{pmatrix}S_{0} & S_{1} \\{- S_{1}^{*}} & S_{0}^{*}\end{pmatrix}}} & \left\lbrack {{Equation}\mspace{14mu} 2} \right\rbrack\end{matrix}$

For antenna (port) #1, only one of the 2 PUCCH resources is selectedaccording to ACK/NACK channel selection, and thus [S₀=S, S₁=0}, {S₀=0,S₁=S}. Accordingly, the following 2 transmission schemes are availableaccording to ACK/NACK channel selection results.

$\begin{matrix}{\begin{matrix}{{Ant}{\# 1}} \\{{Ant}{\# 2}}\end{matrix}\mspace{14mu}\overset{\begin{matrix}{{ch}\; 1} & {{ch}\; 2}\end{matrix}}{\begin{pmatrix}S & 0 \\0 & S^{*}\end{pmatrix}}\mspace{14mu}{or}\mspace{14mu}\begin{matrix}{{Ant}{\# 1}} \\{{Ant}{\# 2}}\end{matrix}\mspace{14mu}\overset{\begin{matrix}{{ch}\; 1} & {{ch}\; 2}\end{matrix}}{\begin{pmatrix}0 & S \\{- S^{*}} & 0\end{pmatrix}}} & \left\lbrack {{Equation}\mspace{14mu} 3} \right\rbrack\end{matrix}$

Table 5 shows an example of SCBC application when ACK/NACK selection isperformed using 4 PUCCH resources. Here, ACK/NACK state mapping at thefirst antenna (i.e. antenna port #1) preferably corresponds to ACK/NACKstate mapping during single antenna (i.e. non-TxD) ACK/NACKtransmission. PUCCHs #0 to #3 indicate PUCCH resources, for example,PUCCH indexes (i.e. n⁽¹⁾ _(PUCCH,0) to n⁽¹⁾ _(PUCCH,3)). PUCCHs #0/#1and PUCCHs #2/#3 form resource pairs for SCBC.

TABLE 5 A/N Antenna port #1 Antenna port #2 state PUCCH#0 PUCCH#1PUCCH#2 PUCCH#3 PUCCH#0 PUCCH#1 PUCCH#2 PUCCH#3 State #0 S0 0 0 0 0 S0*0 0 State #1 S1 0 0 0 0 S1* 0 0 State #2 S2 0 0 0 0 S2* 0 0 State #3 S30 0 0 0 S3* 0 0 State #4 0 S0 0 0 −S0* 0 0 0 State #5 0 S1 0 0 −S1* 0 00 State #6 0 S2 0 0 −S2* 0 0 0 State #7 0 S3 0 0 −S3* 0 0 0 State #8 0 0S0 0 0 0 0 S0* State #9 0 0 S1 0 0 0 0 S1* State #10 0 0 S2 0 0 0 0 S2*State #11 0 0 S3 0 0 0 0 S3* State #12 0 0 0 S0 0 0 −S0* 0 State #13 0 00 S1 0 0 −S1* 0 State #14 0 0 0 S2 0 0 −S2* 0 state #15 0 0 0 S3 0 0−S3* 0

When ACK/NACK selection based ACK/NACK TxD transmission is applied inconsideration of condition #1 and SCBC, the following needs to be takeninto account for PUCCH resource allocation.

When PUCCH #0 and PUCCH #1 (or PUCCH #2 and PUCCH #3) that form an SCBCpair correspond to 2 PUCCH resources linked to one MIMO mode CC, thereis no problem in TxD transmission. However, if PUCCH #0 and PUCCH #1 (orPUCCH #2 and PUCCH #3) correspond to PUCCH resources respectively linkedto non-MIMO mode CC #1 and CC #2, TxD transmission resourcescorresponding to an SCBC pair may not be available. For example, if aPDCCH that schedules non-MIMO mode CC #2 is not successfullyreceived/detected and only a PDCCH that schedules non-MIMO mode CC #1 issuccessfully received/detected, PUCCH #0 is available whereas PUCCH #1is not available. Consequently, a problem that a resource correspondingto antenna port #2 for TxD transmission is not present is generated.

A description will be given of a scheme of efficiently transmittinguplink control information, preferably, ACK/NACK through multipleantennas when a plurality of CCs (in other words, carriers, frequencyresources, cells, etc.) are aggregated, and a resource allocation schemetherefor.

It is assumed that 2 CCs are configured for one UE in the followingdescription for convenience. Furthermore, it is assumed that a maximumof one transport block (or codeword) can be transmitted in a subframe kof a CC when the CC is configured as a non-MIMO mode and up to m (e.g.2) transport blocks (or codewords) can be transmitted in the subframe kof the CC when the CC is configured as a MIMO mode. It is possible torecognize whether the CC is configured as the MIMO mode using atransmission mode configured by a higher layer. In addition, it isassumed that one (non-MIMO) or m (MIMO) ACKs/NACKs are generated for acorresponding CC according to a transmission mode configured for thecorresponding CC irrespective of the number of actually transmittedtransport blocks (or codewords).

Terms used in the specification will now be explained.

-   -   HARQ-ACK: this represents a reception response to a data block,        that is, an ACK/NACK/DTX response (simply, ACK/NACK response).        The ACK/NACK/DTX response means ACK, NACK, DTX or NACK/DTX.        “HARQ-ACK for a specific CC” or “HARQ-ACK of a specific CC”        represents an ACK/NACK response to a data block (e.g. PDSCH)        related to the corresponding CC (e.g. scheduled to the        corresponding CC). An ACK/NACK state means a combination of a        plurality of HARQ-ACKs. Here, the PDSCH can be replaced by a        transport block or a codeword.    -   PUCCH index: this corresponds to a PUCCH resource. The PUCCH        index represents a PUCCH resource index, for example. The PUCCH        resource index is mapped to at least one of an orthogonal cover        (OC), a cyclic shift (CS) and a PRB. When an ACK/NACK selection        scheme is applied, the PUCCH index includes a PUCCH index for        PUCCH format 1b.    -   PUCCH resource linked to a CC: this indicates a PUCCH resource        (refer to Equation 1, implicit PUCCH resource) linked to a PDCCH        corresponding to a PDSCH on the CC, or a PUCCH resource        (explicit PUCCH resource) indicated/allocated by the PDCCH        corresponding to the PDSCH on the CC. The PUCCH resource can be        indicated/allocated using an ARI (ACK/NACK Resource Indicator)        of the PDCCH in an explicit PUCCH resource scheme.    -   ARI: this is used to indicate a PUCCH resource. For example, the        ARI can be used to indicate a resource modification value (e.g.        offset) for a specific PUCCH resource (group) (configured by a        higher layer). Otherwise, the ARI can be used to indicate a        specific PUCCH resource (group) index in a PUCCH resource        (group) set (configured by a higher layer). The ARI can be        included in a TPC (Transmit Power Control) field of a PDCCH        corresponding to a PDSCH on an SCC. PUCCH power control is        performed through a TPC field in a PDCCH (i.e. a PDCCH        corresponding to a PDSCH on a PCC) that schedules the PCC. The        ARI is used with a HARQ-ACK resource indication value.    -   IMP_(P) (Implicit PUCCH resource): this indicates an implicit        PUCCH resource/index linked to a lowest CCE index CCE of a PDCCH        that schedules a PCC (refer to Equation 1). IMP_(P+a) (a being 0        or a positive integer) represents a PUCCH linked to a CCE index        CCE_(P)+a.    -   IMP_(S): this indicates an implicit PUCCH resource/index linked        to a lowest CCE index CCE_(S) of a PDCCH that schedules an SCC        (refer to Equation 1). IMP_(S+b) (b being 0 or a positive        integer) represents a PUCCH linked to a CCE index CCE_(S)+b.    -   EXP_(c) (Explicit PUCCH resource) (c being 0 or a positive        integer): this indicates an explicit PUCCH resource. In case of        explicit PUCCH indexes allocated to a UE, all the indexes may be        consecutive, indexes corresponding to each resource group may be        consecutive, or all the indexes may be independently allocated.        Here, c may be irrelevant to a PUCCH index. The explicit PUCCH        resource can be indicated using the ARI. When the ARI cannot be        used, the explicit PUCCH resource may be a PUCCH resource        previously fixed by higher layer signaling.    -   PCC PDCCH: this indicates a PDCCH that schedules a PCC. That is,        the PCC PDCCH represents a PDCCH corresponding to a PDSCH on the        PCC. The PCC PDCCH is transmitted only on the PCC on the        assumption that cross-carrier scheduling is not permitted for        the PCC.    -   SCC PDCCH: this indicates a PDCCH that schedules an SCC. That        is, the SCC PDCCH represents a PDCCH corresponding to a PDSCH on        the SCC. The SCC PDCCH can be transmitted on the PCC when        cross-carrier scheduling is permitted for the SCC. The SCC PDCCH        is transmitted only on the SCC when cross-carrier scheduling is        not permitted for the SCC.    -   CC scheduling PDCCH: this indicates a PDCCH that schedules a        PDSCH on a corresponding CC. That is, this represents the PDCCH        corresponding to the PDSCH on the CC.    -   SORTD: this is a TxD scheme for transmitting ACK/NACK        information/signal through a plurality of antennas (ports) (e.g.        TX #1 and TX #2) without additionally modifying/coding the        ACK/NACK information/signal. The antennas (ports) transmit        ACK/NACK information/signals corresponding thereto using        different PUCCH resources/indexes. Provided that 2 antennas        (ports) are used, 2 PUCCH resources/indexes for SORTD are        referred to as a “SORTD pair” for convenience. That is, the        first PUCCH resource of the SORTD pair is used for Tx #1        transmission and the second PUCCH resource of the SORTD pair is        used for Tx #2. When SORTD is applied to ACK/NACK selection, as        many PUCCH resources/indexes as twice a maximum number of CWs        that can be transmitted through all CCs allocated to a UE are        needed.    -   Cross-CC scheduling: this denotes an operation of        scheduling/transmitting all PDCCHs through only one PCC.    -   Non-cross-CC scheduling: this denotes an operation of        scheduling/transmitting a PDCCH that schedules each CC through        the CC.

LTE-A, permits cross-carrier scheduling for a DL PCC while allowing onlyself-carrier scheduling for a DL SCC. In this case, a PDCCH thatschedules a PDSCH on the DL PCC can be transmitted only on the DL PCC.On the other hand, a PDCCH that schedules a PDSCH on the DL SCC can betransmitted on the DL PCC (cross-carrier scheduling) or transmitted onthe DL SCC (self-carrier scheduling).

A description will be given of an ACK/NACK selection based PUCCHresource allocation method for ACK/NACK TxD transmission according to anembodiment of the present invention. For TxD ACK/NACK transmission, a BSand a UE can allocate/use 2 implicit PUCCH resources #1 and #2respectively linked to a lowest CCE index n_(CCE) and the following CCEindex n_(CCE)+1 of PDCCHs that schedule CCs irrespective of atransmission mode (MIMO or non-MIMO) configured for each CC (that is, amaximum number of CWs that can be transmitted through each CC), orallocate/use the implicit PUCCH resource #1 and an explicit PUCCHresource. In other words, when ACK/NACK transmission is performedthrough TxD, the total number of PUCCH resources for ACK/NACK selectionis configured as twice the number of CCs allocated to the UE throughhigher layer (e.g. RRC) signaling. Preferably, the PUCCH resource #1 isallocated for ACK/NACK selection during non-TxD ACK/NACK transmission,whereas implicit PUCCH resource #2 linked to a PDCCH that schedules anon-MIMO CC or an explicit PUCCH resource may be allocated/used inaddition to the PUCCH resource #1 during TxD ACK/NACK transmission.Consequently, 2 PUCCH resources (implicit PUCCH resources #1 and #2 orimplicit PUCCH resource #1 and one explicit PUCCH resource) linked toeach CC form an SCBC pair for ACK/NACK TxD transmission.

Tables 6, 7 and 8 illustrate ACK/NACK selection methods based on TxD(SCBC) when 2 CCs are allocated. Table 6 shows a case of MIMO CC+MIMOCC, Table 7 shows a case of MIMO CC+non-MIMO CC, and Table 8 shows acase of non-MIMO CC+non-MIMO CC. MIMO-CC and non-MIMO CC are simplyreferred to as MCC and n-MCC, respectively. Differently from the schemesshown in the following tables, SCBC may be applied to MCC and a schemeof transmitting a symbol S that has not been spatial-coded for antennaport #2 through a separate PUCCH resource (e.g. Spatial OrthogonalResource Transmit Diversity (SORTD)) may be applied to n-MCC. ACK/NACKstate mapping at antenna port #1 may correspond to ACK/NACK statemapping during non-TxD ACK/NACK transmission.

TABLE 6 Antenna port #1 Antenna port #2 A/N MCC #1 MCC #1 MCC #2 MCC #2MCC #1 MCC #1 MCC #2 MCC #2 state PUCCH#1 PUCCH#2 PUCCH#1 PUCCH#2PUCCH#1 PUCCH#2 PUCCH#1 PUCCH#2 State S0 0 0 0 0 S0* 0 0 #0 State S1 0 00 0 S1* 0 0 #1 State S2 0 0 0 0 S2* 0 0 #2 State S3 0 0 0 0 S3* 0 0 #3State 0 S0 0 0 −S0* 0 0 0 #4 State 0 S1 0 0 −S1* 0 0 0 #5 State 0 S2 0 0−S2* 0 0 0 #6 State 0 S3 0 0 −S3* 0 0 0 #7 State 0 0 S0 0 0 0 0 S0* #8State 0 0 S1 0 0 0 0 S1* #9 State 0 0 S2 0 0 0 0 S2* #10 State 0 0 S3 00 0 0 S3* #11 State 0 0 0 S0 0 0 −S0* 0 #12 State 0 0 0 S1 0 0 −S1* 0#13 State 0 0 0 S2 0 0 −S2* 0 #14 State 0 0 0 S3 0 0 −S3* 0 #15

TABLE 7 Antenna port #1 Antenna port #2 MCC MCC n-MCC n-MCC MCC MCCn-MCC n-MCC A/N state PUCCH#1 PUCCH#2 PUCCH#1 PUCCH#2 PUCCH#1 PUCCH#2PUCCH#1 PUCCH#2 State #0 S0 0 0 0 0 S0* 0 0 State #1 S1 0 0 0 0 S1* 0 0State #2 S2 0 0 0 0 S2* 0 0 State #3 S3 0 0 0 0 S3* 0 0 State #4 0 S0 00 −S0* 0 0 0 State #5 0 S1 0 0 −S1* 0 0 0 State #6 0 S2 0 0 −S2* 0 0 0State #7 0 S3 0 0 −S3* 0 0 0 State #8 0 0 S0 0 0 0 0 S0*(or S0) State #90 0 S1 0 0 0 0 S1*(or S1) State #10 0 0 S2 0 0 0 0 S2*(or S2) State #110 0 S3 0 0 0 0 S3*(or S3)

TABLE 8 Antenna port #1 Antenna port #2 n-MCC #1 n-MCC #1 n-MCC #2 n-MCC#2 n-MCC#1 n-MCC #1 n-MCC#2 n-MCC #2 A/N state PUCCH#1 PUCCH#2 PUCCH#1PUCCH#2 PUCCH#1 PUCCH #2 PUCCH#1 PUCCH #2 State #0 S0 0 0 0 0 S0*(or S0)0 0 State #1 S1 0 0 0 0 S1*(or S1) 0 0 State #2 S2 0 0 0 0 S2*(or S2) 00 State #3 S3 0 0 0 0 S3*(or S3) 0 0 State #4 0 0 S0 0 0 0 0 S0*(or S0)State #5 0 0 S1 0 0 0 0 S1*(or S1) State #6 0 0 S2 0 0 0 0 S2*(or S2)State #7 0 0 S3 0 0 0 0 S3*(or S3)

Condition #1 may be suitable for a case in which all PDCCHs arescheduled/transmitted through one DL PCC (i.e. a DL CC linked to a UL CCthat carries ACK/NACK). In other words, implicit PUCCH resources linkedto all PDCCHs scheduled/transmitted through the corresponding PCC can beallocated without colliding with other resources. A case in which PDCCHsare scheduled/transmitted through an SCC (secondary DL CC) other thanthe PCC can be considered. In this case, an implicit PUCCH resourcelinked to a PDCCH on the SCC may collide with an implicit PUCCH resourcelinked to a PDCCH on the PCC. To solve this problem, an ACK/NACKselection scheme that uses an implicit PUCCH resource linked to a PDCCHthat schedules the corresponding CC in case of the PCC and uses anexplicit PUCCH resource in case of the SCC can be considered. Thiscondition is referred to as “condition #2” for convenience.

LTE-A considers a method of allocating an explicit PUCCH resource thatis a reference PUCCH resource through RRC signaling and determining afinal ACK/NACK resource through an ARI (ACK/NACK Resource Indicator) inthe PDCCH for efficient sharing/operation of explicit PUCCH resourcesbetween UEs. The ARI includes an offset value for the reference PUCCHresource, for example.

In condition #2, 2 explicit PUCCH resources linked to the SCC arepreferably allocated such that they have consecutive indexes or at leastexist in the same RB. To achieve this, the following three methods canbe considered.

[Method 1]

-   -   (1) A first PUCCH index is allocated through RRC.    -   (2) An offset to the first PUCCH index is signaled using an ARI.        The offset includes 0 and is set to a positive or negative        multiple of 2.    -   (3) Final two PUCCH indexes are determined by (first PUCCH        index+offset) and (first PUCCH index+offset+1).

FIG. 11 illustrates PUCCH resource allocation according to Method 1.Referring to FIG. 11, a reference PUCCH index allocated by RRC is 3. AnARI in a PDCCH indicates a relative offset with respect to the referencePUCCH index. FIG. 11 shows a case in which offsets indicated by an ARIare {−2, 0, 2, 4}. Dotted line parts in the right of FIG. 11 indicate 2PUCCH indexes finally determined/allocated according to each ARI offset.PUCCH indexes can be indexed such that they wraparound in one RB.

[Method 2]

-   -   (1) A first PUCCH index is allocated through RRC.    -   (2) An offset to the first PUCCH index is signaled using an ARI.        The offset includes 0 and is set to a positive or negative        number corresponding to a multiple of 1.    -   (3) Final two PUCCH indexes are determined by (first PUCCH        index+offset) and (first PUCCH index+offset+1).

FIG. 12 illustrates PUCCH resource allocation according to Method 2.Referring to FIG. 12, a reference PUCCH index allocated by RRC is 2. AnARI in a PDCCH indicates a relative offset with respect to the referencePUCCH index. FIG. 12 shows a case in which offsets indicated by an ARIare {−1, 1, 2}. Dotted line parts in the right of FIG. 11 indicate 2PUCCH indexes finally determined/allocated according to each ARI offset.PUCCH indexes can be indexed such that they wrap around in one RB.

[Method 3]

-   -   (1) A first PUCCH index is allocated through RRC.    -   (2) An offset to the first PUCCH index is signaled using an ARI.        The offset includes 0 and is set to a positive or negative        number corresponding to a multiple of 1.    -   (3) Final two PUCCH indexes are determined by (first PUCCH        index) and (first PUCCH index+offset).

FIG. 13 illustrates PUCCH resource allocation according to Method 3.Referring to FIG. 13, a reference PUCCH index allocated by RRC is 3. AnARI in a PDCCH indicates a relative offset with respect to the referencePUCCH index. FIG. 13 shows a case in which offsets indicated by an ARIare {−2, −1, 1, 2}. In this case, (PUCCH index #3) and (PUCCH index#3+offset) correspond to 2 PUCCH indexes finally determined/allocatedaccording to each ARI offset value. PUCCH indexes can be indexed suchthat they wraparound in one RB.

Application of one of Methods 1, 2 and 3 may be configuredcell-specifically or UE-specifically. A step of offset values signaledby ARIs in Methods 1, 2 and 3 (i.e. whether an offset value is amultiple of 1, a multiple of 2, or a multiple of an integer larger than2) may be configured through RRC signaling. One of states indicated byARIs in Methods 1, 2 and 3 may be configured to indicate use of 2implicit PUCCH resources linked to a PDCCH that schedules an SCC.Alternatively, whether an explicit PUCCH resource is used (option #1) oran implicit PUCCH resource linked to a PDCCH that schedules an SCC isused (option #2) as a PUCCH resource linked to an SCC can be configuredcell-specifically or UE-specifically through RRC signaling.

In case of option #1, the final 2 PUCCH indexes can be determined usingan ARI according to Method 1, 2 or 3 on the basis of the first PUCCHindex allocated by RRC. In case of option #2, an implicit PUCCH indexlinked to the first CCE of a PDCCH that schedules an SCC can be regardedas a reference PUCCH index. In addition, the final 2 PUCCH indexes canbe determined by applying an ARI to the reference PUCCH index accordingto Method 1, 2 or 3 on the basis of PUCCH indexing. Alternatively, thefinal 2 CCE indexes can be determined by applying an ARI to a referenceCCE index (e.g. the first CCE index of a PDCCH that schedules an SCC) onthe basis of CCE indexing according to Method 1, 2 or 3. Then, the 2 CCEindexes are mapped to 2 PUCCH resources, for example, PUCCH indexes.

The above methods have described 2 explicit and/or implicit PUCCHresources. These methods are exemplary and the present invention canalso be applied to 3 or more explicit and/or implicit PUCCH resources.For example, Methods 1 and 2 can be normalized as follows if applicationof an ARI to n (≥2) explicit PUCCH resources is considered.

[Method 4]

-   -   (1) A first PUCCH index is allocated through RRC.    -   (2) An offset to the first PUCCH index is signaled using an ARI.        The offset includes 0 and is set to a positive or negative        number corresponding to a multiple of m (≥n). Here, m may be        predetermined or configured through RRC signaling.    -   (3) Final n PUCCH indexes are determined by (first PUCCH        index+offset), (first PUCCH index+offset+1), . . . (first PUCCH        index+offset+n−1).

Alternatively, to apply an ARI to n (≥2) PUCCH resources (which may beexplicit PUCCH resources allocated by RRC or implicit PUCCH resources),n PUCCH resources can be divided into a plurality of (G) resource groupseach having 2 PUCCH resources. PUCCH resources may be repeated or mayoverlap over PUCCH groups. Specifically, the same ARI value (e.g.offset) can be applied to G PUCCH indexes (corresponding to G PUCCHresource groups) allocated through RRC. Alternatively, Methods 1, 2 and3 can be applied on the basis of n PUCCH indexes independently allocatedthrough RRC. A reference PUCCH index may be previously configured (e.g.as a PUCCH having a lowest or highest index) or directly signaledthrough RRC.

In LTE-A, a DL CC set for a UE can be UE-specifically allocated throughRRC signaling. In view of this, DL CC sets (or the numbers of DL CCs) ofa corresponding UE, which are respectively recognized by a BS and theUE, may be misaligned during DL CC set reconfiguration through RRCsignaling. Accordingly, ACK/NACK feedback may not be normally performedduring a CC reconfiguration period. In case of an ACK/NACK selectionscheme, for example, ACK/NACK state mapping/configuration recognized bythe BS may differ from ACK/NACK state mapping/configuration during a DLCC reconfiguration period.

To solve this problem, when ACK/NACK selection is applied fortransmission of a plurality of ACK/NACKs for a plurality of CCs,transmission of ACK/NACK using an implicit PUCCH resource (refer toEquation 1) linked to a PDCCH that schedules a DL PCC (in other words,DL PCell) may be considered if all CCs (i.e. DL SCCs) (in other words,DL SCells) other than the DL PCC correspond to NACK or DTX. That is, anACK/NACK state in which the DL PCC (or each CW of the DL PCC)corresponds to “A” or “N” and all the DL SCCs (or CWs of the DL SCCs)correspond to “N/D” may be restricted such that the ACK/NACK state usesan implicit PUCCH resource linked to a PDCCH for the DL PCC according toa scheme defined in LTE (which is referred to as “PCC fallback” forconvenience), instead of an explicit PUCCH resource in ACK/NACK statemapping design. For PCC fallback, a PUCCH format used for ACK/NACK statetransmission and a modulation symbol transmitted in the PUCCH format maybe restricted such that they conform to a scheme defined in LTE. Forexample, an ACK/NACK state may be transmitted using PUCCH format 1billustrated in FIG. 7 and a modulation table (refer to Table 2) duringPCC fallback.

When a PCC transmission mode is configured as the non-MIMO mode (singleCW) and 2 ACK/NACK states having “A” or “N” for a PCC and “N/D” for anSCC (or each CW of the SCC) are provided, the ACK/NACK states are mappedto 2 constellation points on a PUCCH resource linked to a PDCCH thatschedules the PCC. Preferably, the 2 constellation points for theACK/NACK states are restricted such that they correspond to 2constellation points defined for PUCCH format 1a ACK/NACK transmissionfor transmission of a single CW in a single CC. Otherwise, the 2constellation points for the ACK/NACK states are restricted such thatthey correspond to 2 constellation points for “AA” and “NN” from among 4constellation points defined for PUCCH format 1b ACK/NACK transmissionin a single CC. That is, ACK/NACK state mapping positions onconstellation are determined on the basis of “A” and “N” of the PCC.Preferably, the ACK/NACK state mapping positions are restricted suchthat “A” and “N” of the PCC correspond to “A” and “N” for PUCCH format1a or “AA” and “NN” for PUCCH format 1b.

When the PCC is configured as the MIMO mode (e.g. 2 CWs or 2 TBs) and 4ACK/NACK states having “A+A”, “A+N”, “N+A” or “N+N” for the PCC and“N/D” for the SCC (or each CW of the SCC) are provided, the ACK/NACKstates are mapped to 4 constellation points on the PUCCH resource linkedto the PDCCH that schedules the PCC. The 4 constellation points for theACK/NACK states preferably correspond to 4 constellation points definedfor PUCCH format 1b ACK/NACK transmission for transmission of 2 CWs in asingle CC. ACK/NACK state mapping positions on constellation aredetermined on the basis of “A” and “N” of each CW of the PCC. In thespecification, “N” of the PCC includes NACK, DTX or NACK/DTX.Preferably, “A” and “N” of each CW of the PCC correspond to “A” and “N”of each CW for PUCCH format 1b on constellation.

FIG. 14 illustrates a PUCCH format 1a/1b based ACK/NACK selection schemefor transmitting single/two CWs in a single CC according to LTE. FIG. 15illustrates an ACK/NACK transmission method according to an embodimentof the present invention when 3 CCs (PCC, CC1 and CC2) are aggregatedand the PCC is configured as the non-MIMO or MIMO transmission mode. Thepresent embodiment is described on the assumption that all SCCs (i.e.CC1 and CC2) are configured as the non-MIMO mode.

Referring to FIGS. 14 and 15, “explicit ACK/NACK selection” is notapplied to an ACK/NACK state having “A” or “N” for the non-MIMO mode PCCand “N/D” for all the SCCs (i.e. PCC fallback). That is, ACK/NACK states(PCC, CC1, CC2)=(A, N/D, N/D), (N, N/D, N/D) are mapped/transmitted toan implicit PUCCH resource linked to a PDCCH that schedules the PCC. Inthis case, mapping between the ACK/NACK states and constellation pointsfollows the LTE rule shown in FIG. 12 on the basis of ACK/NACK for thePCC.

Furthermore, “explicit ACK/NACK selection” is not applied to an ACK/NACKstate having “A+A”, “A+N”, “N+A” or “N+N” for the MIMO mode PCC and“N/D” for all the SCCs (i.e. PCC fallback). In this case, mappingbetween the ACK/NACK states and constellation points follows the LTErule shown in FIG. 14 on the basis of ACK/NACK for the PCC. That is,ACK/NACK states (PCC CW1, PCC CW2, CC1, CC2)=(A, A, N/D, N/D), (A, N,N/D, N/D), (N, A, N/D, N/D), (N, N, N/D, N/D) are mapped/transmitted tothe implicit PUCCH resource linked to a PDCCH that schedules the PCC.

Even when the PCC is configured as the MIMO mode, one or more PDSCHstransmitted on the PCC are scheduled through a single PCC PDCCH.Accordingly, one implicit PUCCH resource is occupied for transmission ofACK/NACK relating to the PCC.

Additionally, the present invention proposes PUCCH resource allocation(RA) for SORTD based ACK/NACK selection and an ARI application scheme.Specifically, the present invention proposes an RA method and ARIapplication scheme in the cross-CC mode and the non-cross-CC mode when 2CCs (i.e. PCC and SCC) are aggregated. Each CC may be configured as theMIMO transmission mode or the non-MIMO transmission mode. In thefollowing description, a PUCCH resource allocated for TX #1 can beidentical to a PUCCH resource allocated for non-TxD based ACK/NACKselection.

Case 1: Case in which Both PCC and SCC are Configured as MIMOTransmission Mode (for Transmission of Up to 4 CWs) and Cross-CCScheduling is Performed

In case 1, it is necessary to allocate a total of 8 PUCCH resources forSORTD based ACK/NACK selection. Since cross-CC scheduling is performed,a PDCCH corresponding to a PDSCH on the SCC is transmitted in the PCC.Accordingly, an implicit PUCCH resource can be allocated as a PUCCHresource linked to the SCC. The following scheme can be considered.

Alt 1-1) Implicit RA Only for TX #1

An implicit PUCCH resource and an explicit PUCCH resource can berespectively allocated to TX #1 and TX #2. 4 PUCCH resource and SORTDpairs allocated to each antenna (port) are listed in the followingtable.

TABLE 9 SORTD pair PCC pair #1 PCC pair #2 SCC pair #1 SCC pair #2 TX #1IMP_(P) IMP_(P+1) IMP_(S) IMP_(S+1) TX #2 EXP₁ EXP₂ EXP₃ EXP₄

In this scheme, an ARI of the SCC PDCCH is preferably used to allocatean additional PUCCH resource for the SCC, preferably, explicit PUCCHresources (i.e. EXP₃ and EXP₄). IMP_(S) (EXP₃) or IMP_(S+1) (EXP₄) isavailable when the SCC PDCCH is successfully received/detected.Accordingly, the ARI of the SCC PDCCH is applicable to EXP₃ and EXP₄. Inthis case, EXP₁ and EXP₂ may indicate PUCCH resources previously fixedby higher layer (e.g. RRC) signaling.

When PCC fallback is applied, the ARI can be applied toallocate/indicate EXP₂ in addition to EXP₃ and EXP₄. This is because anA/N state having NACK/DTX for at least the SCC (or each CW of the SCC)is mapped only to IMP_(P) (EXP₁) when PCC fallback is applied and thusan A/N state mapped to IMP_(P+1) (EXP₂) includes at least one ACK forthe SCC (or each CW of the SCC). That is, IMP_(P+1) (EXP₂) is used whenthe SCC PDCCH is successfully received/detected. Accordingly, the ARI ofthe SCC PDCCH is always applicable to EXP₂. IMP_(P) (EXP₁) may be usedwhen the SCC PDCCH is not successfully received/detected, which meansthat the ARI of the SCC PDCCH cannot always be applied to EXP₁. In thiscase, EXP₁ can indicate a PUCCH resource previously fixed through higherlayer (e.g. RRC) signaling. That is, the ARI can be used toallocate/indicate explicit PUCCH resources corresponding to IMP_(P+1),IMP_(S) and/or IMP_(S+1) when an explicit PUCCH resources correspondingto IMP_(S) and/or IMP_(S+1) or PCC fallback is considered.

When the above description is normalized as “method A”, if all A/Nstates mapped to a PUCCH resource (or a PUCCH resource pair (e.g. SORTDpair) for TxD) include at least one ACK for an SCC (or each CW of theSCC), the ARI of the SCC PDCCH can be used to allocate/indicate thecorresponding PUCCH resource (or corresponding PUCCH resource pair).Allocation/indication of the TxD PUCCH resource pair using the ARI ofthe SCC PDCCH can be performed according to the above-described methods1 to 4, for example. In this case, one of the PUCCH resources of the TxDPUCCH resource pair can be used as a reference resource used to applythe ARI to the other PUCCH resource.

A resource allocated to TX #1 may be identical to a resource allocatedfor non-TxD based ACK/NACK selection. In case of non-TxD, the ARI can beapplied to IMP_(S+1), and to IMP_(P+1) and/or IMP_(S+1) when PCCfallback is considered.

Alt 1-2) Implicit RA for SORTD Pair

2 implicit PUCCH resources and 2 explicit PUCCHs can be respectivelyallocated to SORTD pair #1 and SORTD #2 of each CC. 4 PUCCH resourcesand SORTD pairs allocated to each antenna (port) are listed in thefollowing table. The ARI of the SCC PDCCH can be used toallocate/indicate explicit PUCCH resources (i.e. EXP₃ and EXP₄linked/allocated to the SCC, or EXP₁, EXP₂, EXP₃ and EXP₄ when PCCfallback is considered). When the ARI of the SCC PDCCH is used only forEXP₃ and EXP₄, EXP₁ and EXP₂ may represent PUCCH resources previouslyfixed by higher layer (e.g. RRC) signaling.

TABLE 10 SORTD pair PCC pair #1 PCC pair #2 SCC pair #1 SCC pair #2 TX#1 IMP_(P) EXP₁ IMP_(S) EXP₃ TX #2 IMP_(P+1) EXP₂ IMP_(S+1) EXP₄

Resources allocated to TX #1 may be identical to resources allocated fornon-TxD based ACK/NACK selection. In case of non-TxD, the ARI can beapplied to EXP₃, and to EXP₁ and/or EXP₃ if PCC fallback is considered.

Alt 1-3) Full Implicit RA for all CCs/TXs

Only implicit PUCCH resources can be allocated for all CCs and all TXs.4 PUCCH resources and SORTD pairs allocated to each antenna (port) arelisted in the following table. The ARI of the SCC PDCCH can be used toallocate/indicate implicit PUCCH resources IMP_(S+2) and IMP_(S+3)linked/allocated to the SCC. Considering PCC fallback, the ARI can beused to allocate/indicate (IMP_(S+2), IMP_(S+3)) and/or (IMP_(P+2),IMP_(P+3)). In the present embodiment, the ARI includes an offset valueapplied to reference implicit PUCCH resources (e.g. IMP_(P), IMP_(S),etc.), for example.

TABLE 11 SORTD pair PCC pair #1 PCC pair #2 SCC pair #1 SCC pair #2 TX#1 IMP_(P) IMP_(P+2) IMP_(S) IMP_(S+2) TX #2 IMP_(P+1) IMP_(P+3)IMP_(S+1) IMP_(S+3)

Alt 1-4) RA Considering Single CW Fallback

Provided that an A/N state mapping table in consideration oftransmission of 2 CWs of the MIMO mode CC is made, when a single CW istransmitted in a MIMO mode CC, only part (preferably, half) of the A/Nstate mapping table may be used. Specifically, 2 A/N states having ACKor NACK for transmission of a single CW in the MIMO mode CC can bemapped to two (referred to as “1 CW state”) from among 4 A/N states(i.e. AA, AN, NA and NN) for transmission of 2 CWs in the MIMO mode CC.Considering ACK/NACK constellation of PUCCH format 1a/1b for single CWtransmission in LTE, A and N for a single CW of the MIMO mode CC can berespectively mapped to AA and NN for 2 CWs of the MIMO mode CC. In caseof single CW transmission, when the corresponding CW is regarded as thefirst CW in case of transmission of 2 CWs and the second CW is processedas NACK (or DTX), A and N for the single CW of the MIMO mode CC can berespectively mapped to AN and NN for 2 CWs of the MIMO mode CC.

When 2 CWs are transmitted through the MIMO mode CC, a PDCCH (i.e. DCIformat) that schedules the MIMO mode CC may have a relatively largepayload. Accordingly, a MIMO scheduling PDCCH can be configured of twoor more CCEs. In view of this, 2 implicit PUCCH resources (i.e. IMP #1and IMP #2) respectively linked to a lowest CCE index n_(PDCCH) of thePDCCH that schedules the MIMO mode CC and the following indexn_(PDCCH)+1 can be used when 2 CWs are transmitted through the MIMO modeCC. When a single CW is transmitted through the MIMO mode CC, only asingle implicit PUCCH resource (i.e. IMP or IMP_(S)) linked to thelowest CCE index n_(PDCCH) of the PDCCH that schedules the MIMO mode CCcan be used.

To variably allocate PUCCH resources in consideration of whether asingle CW is transmitted, 1 CW state of the MIMO mode CC should not bemapped/transmitted to/on IMP_(X+a) (X being P or S, a being an integergreater than 1) linked to the PDCCH that schedules the MIMO mode CC.This condition is referred to as “condition #3” for convenience.Condition #3 is configured because IMP_(X+a) may not be availablebecause a PDCCH for single CW transmission can be configured of only oneCCE.

When condition #3 is not satisfied (that is, 1 CW state is mapped to thesecond PUCCH resource pair linked to the corresponding CC), IMP_(X+a)can be replaced by an explicit PUCCH resource for securing PUCCHresources. Condition #3 may be satisfied according to A/N state mappingfor ACK/NACK selection. That is, 2 implicit PUCCH resources can beallocated to a CC that satisfies condition #3, whereas one implicitPUCCH resource and one explicit PUCCH resource can be allocated to a CCthat does not satisfy condition #3.

Specifically, Alt 1-1 is applicable when both a PCC and an SCC meetcondition #3, whereas Alt 1-2 is applicable when both the PCC and SCC donot satisfy condition #3.

When only the PCC satisfies condition #3, the following two resourceallocation schemes can be considered. Resource allocation schemesaccording to Tables 12 and 13 are respectively referred to as RA 1-1 andRA 1-2 for convenience. Referring to Tables 12 and 13, 2 implicit PUCCHresources are allocated for the PCC and one implicit PUCCH resource andone explicit PUCCH resource are allocated for the SCC in case of TX #1.PUCCH resources for TX #2 can be applied using the various methodsdescribed above.

TABLE 12 SORTD pair PCC pair #1 PCC pair #2 SCC pair #1 SCC pair #2 TX#1 IMP_(P) IMP_(P+1) IMP_(S) EXP₃ TX #2 EXP₁ EXP₂ IMP_(S+1) EXP₄

TABLE 13 SORTD pair PCC pair #1 PCC pair #2 SCC pair #1 SCC pair #2 TX#1 IMP_(P) IMP_(P+1) IMP_(S) EXP₄ TX #2 EXP₁ EXP₂ EXP₃ EXP₅

In case of RA 1-1, the ARI of the SCC PDCCH can be applied to explicitPUCCH resources (e.g. EXP₃ and EXP₄ linked/allocated to the SCC, orEXP₂, EXP₃ and EXP₄ when PCC fallback is considered) that satisfy methodA (refer to Alt 1-1). Resources allocated to TX #1 may be identical toresources allocated for non-TxD based ACK/NACK selection. In case ofnon-TxD, the ARI can be applied to EXP₃, or to IMP_(P+1) and/or EXP₃when PCC fallback is considered.

In case of RA 1-2, the ARI of the SCC PDCCH can be applied to explicitPUCCH resources (e.g. EXP₃, EXP₄ and EXP₅ linked/allocated to the SCC,or EXP₂, EXP₃, EXP₄ and EXP₅ when PCC fallback is considered) thatsatisfy method A. Resources allocated to TX #1 may be identical toresources allocated for non-TxD based ACK/NACK selection. In case ofnon-TxD, the ARI can be applied to EXP₄, or to IMP_(P+1) and/or EXP₄when PCC fallback is considered.

When only the SCC satisfies condition #3, the following 2 resourceallocation schemes can be considered. Resource allocation schemesaccording to Tables 14 and 15 are respectively referred to as RA 2-1 andRA 2-2 for convenience. Referring to Tables 12 and 13, 2 implicit PUCCHresources are allocated for the SCC and one implicit PUCCH resource andone explicit PUCCH resource are allocated for the PCC in case of TX #1.PUCCH resources for TX #2 can be applied using the various methodsdescribed above.

TABLE 14 SORTD pair PCC pair #1 PCC pair #2 SCC pair #1 SCC pair #2 TX#1 IMP_(P) EXP₁ IMP_(S) IMP_(S+1) TX #2 IMP_(P+1) EXP₂ EXP₃ EXP₄

TABLE 15 SORTD pair PCC pair #1 PCC pair #2 SCC pair #1 SCC pair #2 TX#1 IMP_(P) EXP₂ IMP_(S) IMP_(S+1) TX #2 EXP₁ EXP₃ EXP₄ EXP₅

In case of RA 2-1, the ARI of the SCC PDCCH can be applied to explicitPUCCH resources (e.g. EXP₃ and EXP₄ linked/allocated to the SCC, orEXP₁, EXP₂, EXP₃ and EXP₄ when PCC fallback is considered) that satisfymethod A (refer to Alt 1-1). Resources allocated to TX #1 may beidentical to resources allocated for non-TxD based ACK/NACK selection.In case of non-TxD, the ARI can be applied to IMP_(S+1), or to IMP_(S+1)and/or EXP₁ when PCC fallback is considered.

In case of RA 2-2, the ARI of the SCC PDCCH can be applied to explicitPUCCH resources (e.g. EXP₄ and EXP₅ linked/allocated to the SCC, orEXP₂, EXP₃, EXP₄ and EXP₅ when PCC fallback is considered) that satisfymethod A. Resources allocated to TX #1 may be identical to resourcesallocated for non-TxD based ACK/NACK selection. In case of non-TxD, theARI can be applied to IMP_(S+1), or to IMP_(S+1) and/or EXP₂ when PCCfallback is considered.

In the following description, when condition #3 is satisfied for theMIMO mode CC, it is apparent that a scheme in which resources allocatedto the corresponding CC are configured of 2 implicit PUCCH resources (incase of TX #1) can be applied. When condition #3 is not satisfied forthe MIMO mode CC, it is apparent that a scheme in which resourcesallocated to the CC correspond to a combination of an implicit PUCCHresource and an explicit PUCCH resource can be applied.

Case 2: Case in which Both PCC and SCC are Configured as MIMOTransmission Mode (for Transmission of Up to 4 CWs) and Non-Cross-CCScheduling is Performed

In case 2, it is necessary to allocate a total of 8 PUCCH resources forSORTD based ACK/NACK selection. Since non-cross-CC scheduling isperformed, a PDCCH corresponding to a PDSCH on the SCC is transmitted inthe SCC. Accordingly, an explicit PUCCH resource rather than an implicitPUCCH resource can be preferentially allocated as a PUCCH resourcelinked to the SCC in order to prevent collision of implicit PUCCHresources between UEs. The following scheme can be considered.

Alt 2-1) Implicit RA Only for PCC TX #1

Implicit PUCCH resources can be allocated to TX #1 of the PCC andexplicit PUCCH resources can be allocated to the others. 4 PUCCHresource and SORTD pairs allocated to each antenna (port) are listed inthe following table. In this scheme, the ARI of the SCC PDCCH can beapplied to allocate/indicate explicit PUCCH resources (e.g. EXP₃, EXP₄,EXP₅ and EXP₆ linked/allocated to the SCC, or EXP₂, EXP₃, EXP₄, EXP₅ andEXP₆ when PCC fallback is considered) that satisfy method A (refer toAlt 1-1).

TABLE 16 SORTD pair PCC pair #1 PCC pair #2 SCC pair #1 SCC pair #2 TX#1 IMP_(P) IMP_(P+1) EXP₃ EXP₅ TX #2 EXP₁ EXP₂ EXP₄ EXP₆

Resources allocated to TX #1 may be identical to resources allocated fornon-TxD based ACK/NACK selection. In case of non-TxD, the ARI can beapplied to EXP₃ and EXP₅, or to IMP_(P+i), EXP₃ and/or EXP₅ when PCCfallback is considered.

Alt 2-2) Implicit RA for PCC SORTD Pair

2 implicit PUCCH resources can be allocated for PCC SORTD pair #1 andexplicit PUCCH resources can be allocated for the others. 4 PUCCHresource and SORTD pairs allocated to each antenna (port) are listed inthe following table. In this case, the ARI of the SCC PDCCH can beapplied to explicit PUCCH resources (particularly, EXP₃, EXP₄, EXP₅ andEXP₆ linked/allocated to the SCC, or EXP₁, EXP₂, EXP₃, EXP₄, EXP₅ andEXP₆ when PCC fallback is considered) that satisfy method A.

TABLE 17 SORTD pair PCC pair #1 PCC pair #2 SCC pair #1 SCC pair #2 TX#1 IMP_(P) EXP₁ EXP₃ EXP₅ TX #2 IMP_(P+1) EXP₂ EXP₄ EXP₆

Resources allocated to TX #1 may be identical to resources allocated fornon-TxD based ACK/NACK selection. In case of non-TxD, the ARI can beapplied to EXP₃ and EXP₅, or to EXP₁, EXP₃ and EXP₅ when PCC fallback isconsidered.

Alt 2-3) Full Implicit RA Only for PCC

Only implicit PUCCH resources can be allocated for the PCC and onlyexplicit PUCCH resources can be allocated for the SCC. 4 PUCCH resourceand SORTD pairs allocated to each antenna (port) are listed in thefollowing table. The ARI of the SCC PDCCH can be applied to PUCCHresources (e.g., EXP₁, EXP₂, EXP₃ and EXP₄ linked/allocated to the SCC,or (IMP_(P+2), IMP_(P+3)) and/or (EXP₁, EXP₂, EXP₃, EXP₄) when PCCfallback is considered) that satisfy method A.

TABLE 18 SORTD pair PCC pair #1 PCC pair #2 SCC pair #1 SCC pair #2 TX#1 IMP_(P) IMP_(P+2) EXP₁ EXP₃ TX #2 IMP_(P+1) IMP_(P+3) EXP₂ EXP₄

Case 3: Case in which PCC and SCC are Respectively Configured as MIMOMode and Non-MIMO Mode (for Transmission of Up to 3 CWs) and Cross-CCScheduling is Performed

In case 3, it is necessary to allocate a total of 6 PUCCH resources forSORTD based ACK/NACK selection. Since cross-CC scheduling is performed,a PDCCH corresponding to a PDSCH on the SCC is transmitted in the PCC.Accordingly, an implicit PUCCH resource can be allocated as a PUCCHresource linked to the SCC. The following scheme can be considered.

Alt 3-1) Implicit RA Only for PCC TX #1 and SCC SORTD Pair

Implicit PUCCH resources can be allocated to PCC TX #1 and SCC SORTDpair and explicit PUCCH resources can be allocated to PCC TX #2. 3 PUCCHresource and SORTD pairs allocated to each antenna (port) are listed inthe following table. The ARI of the SCC PDCCH is preferably applied toan implicit PUCCH having a larger value of b from among resources(satisfying method A (refer to Alt 1-1)) linked/allocated to the SCC,IMP_(S+b) (b=0, 1), that is, IMP_(S+1). Considering PCC fallback, theARI can be applied to IMP_(S+1) and/or EXP₂.

TABLE 19 SORTD pair PCC pair #1 PCC pair #2 SCC pair #1 TX #1 IMP_(P)IMP_(P+1) IMP_(S) TX #2 EXP₁ EXP₂ IMP_(S+1)

Resources allocated to TX #1 may be identical to resources allocated fornon-TxD based ACK/NACK selection. In case of non-TxD, the ARI can beapplied to IMP_(S), or to IMP_(P+1) and/or IMP_(S) when PCC fallback isconsidered.

Alt 3-2) Implicit RA for SORTD Pair

An implicit PUCCH resource can be allocated to SORTD pair #1 of each CCand an explicit PUCCH resource can be allocated to SORTD pair #2 of eachCC. 3 PUCCH resource and SORTD pairs allocated to each antenna (port)are listed in the following table. The ARI of the SCC PDCCH ispreferably applied to an implicit PUCCH having a larger value of b fromamong resources (satisfying method A) linked/allocated to the SCC,IMP_(S+b) (b=0, 1), that is, IMP_(S+1). Considering PCC fallback, theARI can be applied to IMP_(S+1) and/or (EXP₁, EXP₂).

TABLE 20 SORTD pair PCC pair #1 PCC pair #2 SCC pair #1 TX #1 IMP_(P)EXP₁ IMP_(S) TX #2 IMP_(P+1) EXP₂ IMP_(S+1)

Resources allocated to TX #1 may be identical to resources allocated fornon-TxD based ACK/NACK selection. In case of non-TxD, the ARI can beapplied to IMP_(S), or to EXP₁ and/or IMP_(S) when PCC fallback isconsidered.

Alt 3-3) Full Implicit RA for all CCs/TXs

Only implicit PUCCH resources can be allocated to all CCs and all TXs. 3PUCCH resource and SORTD pairs allocated to each antenna (port) arelisted in the following table. The ARI of the SCC PDCCH is preferablyapplied to an implicit PUCCH having a larger value of b from amongresources (satisfying method A) linked/allocated to the SCC, IMP_(S+b)(b=0, 1), that is, IMP_(S+1). Considering PCC fallback, the ARI can beapplied to IMP_(S+1) and/or (IMP_(P+2), IMP_(P+3)).

TABLE 21 SORTD pair PCC pair #1 PCC pair #2 SCC pair #1 TX #1 IMP_(P)IMP_(P+2) IMP_(S) TX #2 IMP_(P+1) IMP_(P+3) IMP_(S+1)

Case 4: Case in which PCC and SCC are Respectively Configured as MIMOMode and Non-MIMO Mode (for Transmission of Up to 3 CWs) andNon-Cross-CC Scheduling is Performed

In case 4, it is necessary to allocate a total of 6 PUCCH resources forSORTD based ACK/NACK selection. Since non-cross-CC scheduling isperformed, a PDCCH corresponding to a PDSCH on the SCC is transmitted inthe SCC. Accordingly, an explicit PUCCH resource rather than an implicitPUCCH resource can be preferentially allocated as a PUCCH resourcelinked to the SCC in order to prevent collision of implicit PUCCHresources between UEs. The following scheme can be considered.

Alt 4-1) Implicit RA Only for PCC TX #1

Implicit PUCCH resources can be allocated to PCC TX #1 and explicitPUCCH resources can be allocated to the others. 3 PUCCH resource andSORTD pairs allocated to each antenna (port) are listed in the followingtable. The ARI of the SCC PDCCH can be applied to explicit PUCCHresources (e.g. EXP₃ and EXP₄ linked/allocated to the SCC, or EXP₂, EXP₃and EXP₄ when PCC fallback is considered) that satisfy method A (referto Alt 1-1)).

TABLE 22 SORTD pair PCC pair #1 PCC pair #2 SCC pair #1 TX #1 IMP_(P)IMP_(P+1) EXP₃ TX #2 EXP₁ EXP₂ EXP₄

Resources allocated to TX #1 may be identical to resources allocated fornon-TxD based ACK/NACK selection. In case of non-TxD, the ARI can beapplied to EXP₃, or to IMP_(P+1) and/or EXP₃ when PCC fallback isconsidered.

Alt 4-2) Implicit RA for PCC SORTD Pair

Implicit PUCCH resources can be allocated to PCC SORTD pair #1 andexplicit PUCCH resources can be allocated to the others. 3 PUCCHresource and SORTD pairs allocated to each antenna (port) are listed inthe following table. The ARI of the SCC PDCCH can be applied to explicitPUCCH resources (e.g. EXP₃ and EXP₄ linked/allocated to the SCC, orEXP₁, EXP₂, EXP₃ and EXP₄ when PCC fallback is considered) that satisfymethod A.

TABLE 23 SORTD pair PCC pair #1 PCC pair #2 SCC pair #1 TX #1 IMP_(P)EXP₁ EXP₃ TX #2 IMP_(P+1) EXP₂ EXP₄

Resources allocated to TX #1 may be identical to resources allocated fornon-TxD based ACK/NACK selection. In case of non-TxD, the ARI can beapplied to EXP₃, or to EXP₁ and EXP₃.

Alt 4-3) Full Implicit RA Only for PCC

Implicit PUCCH resources can be allocated to the PCC and explicit PUCCHresources can be allocated to the SCC. 3 PUCCH resource and SORTD pairsallocated to each antenna (port) are listed in the following table. TheARI of the SCC PDCCH can be applied to explicit PUCCH resources (e.g.EXP₁ and EXP₂ linked/allocated to the SCC, or (IMP_(P+2), IMP_(P+3))and/or (EXP₁, EXP₂) when PCC fallback is considered) that satisfy methodA.

TABLE 24 SORTD pair PCC pair #1 PCC pair #2 SCC pair #1 TX #1 IMP_(P)IMP_(P+2) EXP₁ TX #2 IMP_(P+1) IMP_(P+3) EXP₂

Case 5: Case in which PCC and SCC are Respectively Configured asNon-MIMO Mode and MIMO Mode (for Transmission of Up to 3 CWs) andCross-CC Scheduling is Performed

In case 5, it is necessary to allocate a total of 6 PUCCH resources forSORTD based ACK/NACK selection. Since cross-CC scheduling is performed,a PDCCH corresponding to a PDSCH on the SCC is transmitted in the PCC.Accordingly, an implicit PUCCH resource can be allocated as a PUCCHresource linked to the SCC. The following scheme can be considered.

Alt 5-1) Implicit RA for PCC SORTD Pair and TX #1

Implicit PUCCH resources can be allocated to PCC SORTD pair and SCC TX#1 and explicit PUCCH resources can be allocated to SCC TX #2. 3 PUCCHresource and SORTD pairs allocated to each antenna (port) are listed inthe following table. The ARI of the SCC PDCCH can be applied to explicitPUCCHs (EXP₁, EXP₂) that satisfy method A (refer to Alt 1-1).

TABLE 25 SORTD pair PCC pair #1 SCC pair #1 SCC pair #2 TX #1 IMP_(P)IMP_(S) IMP_(S+1) TX #2 IMP_(P+1) EXP₁ EXP₂

Resources allocated to TX #1 may be identical to resources allocated fornon-TxD based ACK/NACK selection. In case of non-TxD, the ARI can beapplied to IMP_(S) and/or IMP_(S+1).

Alt 5-2) Implicit RA for SORTD Pair

An implicit PUCCH resource can be allocated to SORTD pair #1 of each CCand an explicit PUCCH resource can be allocated to SORTD pair #2 of eachCC. 3 PUCCH resource and SORTD pairs allocated to each antenna (port)are listed in the following table. The ARI of the SCC PDCCH can beapplied to explicit PUCCH resources (EXP₁, EXP₂) that satisfy method A.

TABLE 26 SORTD pair PCC pair #1 SCC pair #1 SCC pair #2 TX #1 IMP_(P)IMP_(S) EXP₁ TX #2 IMP_(P+1) IMP_(S+1) EXP₂

Resources allocated to TX #1 may be identical to resources allocated fornon-TxD based ACK/NACK selection. In case of non-TxD, the ARI can beapplied to EXP₁ and/or IMP_(S).

Alt 5-3) Full Implicit RA for all CCs/TXs

Only implicit PUCCH resources can be allocated to all CCs and all TXs. 3PUCCH resource and SORTD pairs allocated to each antenna (port) arelisted in the following table. The ARI of the SCC PDCCH is preferablyapplied to implicit PUCCH resources having a larger value of b fromamong resources (satisfying method A) linked/allocated to the SCC,IMP_(S+b) (b=0, 1, 2, 3), that is, IMP_(S+2) and IMP_(S+3).

TABLE 27 SORTD pair PCC pair #1 SCC pair #1 SCC pair #2 TX #1 IMP_(P)IMP_(S) IMP_(S+2) TX #2 IMP_(P+1) IMP_(S+1) IMP_(S+3)

Case 6: Case in which PCC and SCC are Respectively Configured asNon-MIMO Mode and MIMO Mode (for Transmission of Up to 3 CWs) andNon-Cross-CC Scheduling is Performed

In case 6, it is necessary to allocate a total of 6 PUCCH resources forSORTD based ACK/NACK selection. In this case, implicit PUCCH resourcescan be allocated to PCC SORTD pairs and explicit PUCCH resources can beallocated to the others. 3 PUCCH resource and SORTD pairs allocated toeach antenna (port) are listed in the following table. The ARI of theSCC PDCCH can be applied to explicit PUCCH resources (e.g. EXP₁, EXP₂,EXP₃ and EXP₄ that satisfy method A (refer to Alt 1-1)).

TABLE 28 SORTD pair PCC pair #1 SCC pair #1 SCC pair #2 TX #1 IMP_(P)EXP₁ EXP₃ TX #2 IMP_(P+1) EXP₂ EXP₄

Resources allocated to TX #1 may be identical to resources allocated fornon-TxD based ACK/NACK selection. In case of non-TxD, the ARI can beapplied to EXP₁ and EXP₃.

Case 7: Case in which Both PCC and SCC are Configured as Non-MIMO Mode(for Transmission of Up to 2 CWs) and Cross-CC Scheduling is Performed

In case 7, it is necessary to allocate a total of 4 PUCCH resources forSORTD based ACK/NACK selection. In this case, only implicit PUCCHresources can be allocated to all CCs and all TXs. 2 PUCCH resource andSORTD pairs allocated to each antenna (port) are listed in the followingtable. The ARI of the SCC PDCCH is preferably applied to an implicitPUCCH resource having a larger value of b from among resources(satisfying method A) linked/allocated to the SCC, IMP_(S+b) (b=0, 1),that is, IMP_(S+1).

TABLE 29 SORTD pair PCC pair #1 SCC pair #1 TX #1 IMP_(P) IMP_(S) TX #2IMP_(P+1) IMP_(S+1)

Resources allocated to TX #1 may be identical to resources allocated fornon-TxD based ACK/NACK selection. In case of non-TxD, the ARI can beapplied to IMP_(S).

Case 8: Case in which Both PCC and SCC are Configured as Non-MIMO Mode(for Transmission of Up to 2 CWs) and Non-Cross-CC Scheduling isPerformed

In case 8, it is necessary to allocate a total of 4 PUCCH resources forSORTD based ACK/NACK selection. In this case, implicit PUCCH resourcescan be allocated to PCC SORTD pairs and explicit PUCCH resources can beapplied to SCC SORTD pairs. 2 PUCCH resource and SORTD pairs allocatedto each antenna (port) are listed in the following table. The ARI of theSCC PDCCH is preferably applied to explicit PUCCH resources (e.g. EXP₁and EXP₂) that satisfy method A (refer to Alt 1-1).

TABLE 30 SORTD pair PCC pair #1 SCC pair #1 TX #1 IMP_(P) EXP₁ TX #2IMP_(P+1) EXP₂

Resources allocated to TX #1 may be identical to resources allocated fornon-TxD based ACK/NACK selection. In case of non-TxD, the ARI can beapplied to EXP₁.

The above-described methods 1, 2, 3 and 4 can be used for application ofthe ARI proposed in cases 1 to 8. Specifically, the ARI can indicate 1)offset value for a PUCCH resource to which the ARI is applied, orindicate 2) offset value or whether an implicit PUCCH resource is usedor not (when an explicit PUCCH resource is reserved). In addition, theARI can indicate 3) resource (group) index in a predefined PUCCHresource (group) set to which the ARI is applied, or indicate 4)resource (group) index in a set or whether an implicit PUCCH resource isused or not. Here, when the ARI is applied to an implicit PUCCH, the ARIcan be used as an offset value for a PUCCH index allocated through theabove-mentioned schemes or an offset value for a CCE index linked to anallocated PUCCH index. When a single ARI is applied to both implicit andexplicit PUCCH resources, the ARI can be used to indicate 5) offsetvalues for both the implicit and explicit PUCCH resources (here, offsetstep values may be configured differently for the implicit PUCCHresource and the explicit PUCCH resource), or indicate 6) offset valuefor the implicit PUCCH resource and an index in a set for the explicitPUCCH resource.

Cases 1 to 8 propose RA and ARI schemes suitable for each of thecross-CC mode and non-cross-CC mode by distinguishing the cross-CC modeand non-cross-CC mode from each other. However, the RA and ARI schemesproposed in cases 1 to 8 can be applied according to schedulingcapability of the BS and PUCCH resource load without discriminatingbetween the cross-CC mode and the non-cross-CC mode. In other words,cases 1, 3, 5 and 7 may be applied to the non-cross-CC mode and cases 2,4, 6 and 8 may be applied to the cross-CC mode.

It is apparent that all schemes proposed in cases 1 to 8 are applicablewhen a plurality of SCCs is present. Specifically, a scheme ofperforming RA for a PCC and SCCs according to a combination of two ofthe schemes of cases 1 to 8 can be considered.

<S1> Case of MIMO Mode PCC and Cross-CC Scheduling

-   -   Rule 1-1) SCC RA of Alt 1-1 (i.e. implicit RA only for TX #1)        can be applied to a MIMO mode SCC and SCC RA of Alt 3-1 (i.e.        implicit RA for SORTD pair) can be applied to a non-MIMO mode        SCC. In case of the PCC, PCC RA of Alt 1-1/3-1 (i.e. implicit RA        only for TX #1) can be applied. Resources allocated to TX #1 may        be identical to resources allocated for non-TxD based ACK/NACK        selection.    -   Rule 1-2) SCC RA of Alt 1-2 can be applied to the MIMO mode SCC        and SCC RA of Alt 3-2 can be applied to the non-MIMO mode SCC.        In case of the PCC, PCC RA of Alt 1-2/3-2 can be applied.        Resources allocated to TX #1 may be identical to resources        allocated for non-TxD based ACK/NACK selection.    -   Rule 1-3) SCC RA of Alt 1-3 can be applied to the MIMO mode SCC        and SCC RA of Alt 3-3 can be applied to the non-MIMO mode SCC.        In case of the PCC, PCC RA of Alt 1-3/3-3 can be applied.        Resources allocated to TX #1 may be identical to resources        allocated for non-TxD based ACK/NACK selection.

<S2> Case of MIMO Mode PCC and Non-Cross-CC Scheduling

-   -   Rule 2-1) SCC RA of Alt 2-1 can be applied to the MIMO mode SCC        and SCC RA of Alt 4-1 can be applied to the non-MIMO mode SCC.        In case of the PCC, PCC RA of Alt 2-1/4-1 can be applied.        Resources allocated to TX #1 may be identical to resources        allocated for non-TxD based ACK/NACK selection.    -   Rule 2-2) SCC RA of Alt 2-2 can be applied to the MIMO mode SCC        and SCC RA of Alt 4-2 can be applied to the non-MIMO mode SCC.        In case of the PCC, PCC RA of Alt 2-2/4-2 can be applied.        Resources allocated to TX #1 may be identical to resources        allocated for non-TxD based ACK/NACK selection.    -   Rule 2-3) SCC RA of Alt 2-3 can be applied to the MIMO mode SCC        and SCC RA of Alt 4-3 can be applied to the non-MIMO mode SCC.        In case of the PCC, PCC RA of Alt 2-3/4-3 can be applied.        Resources allocated to TX #1 may be identical to resources        allocated for non-TxD based ACK/NACK selection.

<S3> Case of Non-MIMO Mode PCC and Cross-CC Scheduling

-   -   Rule 3-1) SCC RA of Alt 5-1 can be applied to the MIMO mode SCC        and SCC RA of case 7 can be applied to the non-MIMO mode SCC. In        case of the PCC, PCC RA of Alt 5-1/case 7 can be applied.        Resources allocated to TX #1 may be identical to resources        allocated for non-TxD based ACK/NACK selection.    -   Rule 3-2) SCC RA of Alt 5-2 can be applied to the MIMO mode SCC        and SCC RA of case 7 can be applied to the non-MIMO mode SCC. In        case of the PCC, PCC RA of Alt 5-2/case 7 can be applied.        Resources allocated to TX #1 may be identical to resources        allocated for non-TxD based ACK/NACK selection.    -   Rule 3-3) SCC RA of Alt 5-3 can be applied to the MIMO mode SCC        and SCC RA of case 7 can be applied to the non-MIMO mode SCC. In        case of the PCC, PCC RA of Alt 5-3/case 7 can be applied.        Resources allocated to TX #1 may be identical to resources        allocated for non-TxD based ACK/NACK selection.

<S4> Case of Non-MIMO Mode PCC and Non-Cross-CC Scheduling

-   -   Rule 4) SCC RA of case 6 can be applied to the MIMO mode SCC and        SCC RA of case 8 can be applied to the non-MIMO mode SCC. In        case of the PCC, PCC RA of case 6/case 8 can be applied.        Resources allocated to TX #1 may be identical to resources        allocated for non-TxD based ACK/NACK selection.        Preferably, rules 1-1, 2-1, 3-1 and 4 may be applied according        to a PCC transmission mode and whether cross-CC scheduling is        performed in case of non-TxD based ACK/NACK selection, and rules        1-2, 2-2, 3-2 and 4 may be applied according to a PCC        transmission mode and whether cross-CC scheduling is performed        in case of TxD (e.g. SORTD) based ACK/NACK selection.

In an LTE-A TDD system, a case in which a plurality of CCs is aggregatedcan be considered. Accordingly, the LTE-A TDD system considerstransmission of a plurality of ACK/NACK information/signals for aplurality of PDSCHs transmitted through a plurality of DL subframes(SFs) and a plurality of DL CCs, through a specific UL CC (that is, A/NCC) in UL subframes corresponding to the plurality of DL subframes. Inthis respect, it is possible to consider a scheme (i.e. full ACK/NACKscheme) of transmitting a plurality of ACKs/NACKs corresponding to amaximum number of CWs that can be transmitted through all DL CCsallocated to a UE, for all DL subframes. Furthermore, it is possible toconsider a scheme (i.e. bundled ACK/NACK scheme) of bundling a pluralityof ACKs/NACKs corresponding to a maximum number of CWs that can betransmitted through all DL CCs allocated to a UE, in CW and/or CC and/orsubframe domain to reduce the number of ACKs/NACKs to be transmitted andtransmitting ACKs/NACKs. CW bundling means ACK/NACK bundling applied foreach DL CC in each DL subframe. CC bundling means ACK/NACK bundlingapplied for all or some DL CCs in each DL subframe. Subframe bundlingmeans ACK/NACK bundling applied for all or some DL subframes in each DLCC. ACK/NACK bundling means a logical-AND operation of ACK/NACK results.

A description will be given of a PUCCH RA method for non-TxDtransmission based ACK/NACK selection in a CA based TDD system.Specifically, 4-bit ACK/NACK transmission (which requires allocation ofup to 4 PUCCH resources) is described. It is assumed that 2 CCs (i.e. aPCC and an SCC) in the non-MIMO mode are aggregated and DL SF:UL SF=2:1for convenience. Terms used in the following description will now beexplained.

-   -   PUCCH resource linked to SF: this indicates a PUCCH resource        (refer to Equation 1, implicit PUCCH resource) linked to a PDCCH        corresponding to a PDSCH on a corresponding SF, or a PUCCH        resource (explicit PUCCH resource) indicated by a PDCCH        corresponding to a PDSCH on a corresponding CC. This can be        indicated using an ARI (ACK/NACK Resource Indicator) of the        PDCCH in the explicit PUCCH resource scheme. In case of CC        aggregation, a PUCCH resource linked to an SF can be allocated        on a CC basis.    -   PUCCH resource linked to CC: this indicates a PUCCH resource        (refer to Equation 1, implicit PUCCH resource) linked to a PDCCH        corresponding to a PDSCH on a corresponding CC, or a PUCCH        resource (explicit PUCCH resource) indicated by the PDCCH        corresponding to the PDSCH on the corresponding CC. This can be        indicated using an ARI of the PDCCH in the explicit PUCCH        resource scheme. In a TDD system, a PUCCH resource linked to a        CC can be allocated on a subframe basis.    -   IMP_(Pn): this indicates an implicit PUCCH resource/index linked        to a lowest CCE index CCE_(Pn) of a PDCCH corresponding to a        PDSCH on a PCC transmitted in an n-th SF. IMP_(Pn+d) indicates a        PUCCH resource/index linked to CCE_(Pn+d).    -   IMP_(Sn): this indicates an implicit PUCCH resource/index linked        to a lowest CCE index CCE_(Sn) of a PDCCH corresponding to a        PDSCH on an SCC transmitted in an n-th SF. IMP_(Sn+e) indicates        a PUCCH resource/index linked to CCE_(Sn+e).

The PUCCH RA method for non-TxD transmission based ACK/NACK selection ina CA based TDD system is described in detail.

TDD RA 1) Full Implicit RA

Only implicit PUCCH resources can be allocated all CCs and all SFs.

TABLE 31 PCC SCC SF #1 IMP_(P1) IMP_(S1) SF #2 IMP_(P2) IMP_(S2)

When SORTD transmission is supported, the following PUCCH resourceallocation scheme can be applied. In Tables 32, 33 and 34, resources inparentheses indicate resources added to configure SORTD pairs. The ARIof the SCC PDCCH is preferably used to allocate an explicit PUCCHresource for the SCC. IMP_(S1) or IMP_(S2) is available when the SCCPDCCH is successfully received/detected. Accordingly, the ARI of the SCCPDCCH can always be used to allocate/indicate explicit PUCCH resourceslinked to the SCC (Table 33: EXP₃ and EXP₄ and Table 34: EXP₁ and EXP₂).In Table 33, explicit PUCCH resources EXP₁ and EXP₂ linked to the PCCcan indicate PUCCH resources previously fixed by higher layer (e.g. RRC)signaling. The ARI can be applied according to methods 1 to 4.

TABLE 32 PCC SCC SF #1 IMP_(P1) (IMP_(P1+1)) IMP_(S1) (IMP_(S1+1)) SF #2IMP_(P2) (IMP_(P2+1)) IMP_(S2) (IMP_(S2+1))

TABLE 33 PCC SCC SF #1 IMP_(P1) (EXP₁) IMP_(S1) (EXP₃) SF #2 IMP_(P2)(EXP₂) IMP_(S2) (EXP₄)

TABLE 34 PCC SCC SF #1 IMP_(P1) (IMP_(P1+1)) IMP_(S1) (EXP₁) SF #2IMP_(P2) (IMP_(P2+1)) IMP_(S2) (EXP₂)

TDD RA 2) Implicit RA Only for SF #1

Only implicit PUCCH resources can be applied to SF #1 as follows.

TABLE 35 PCC SCC SF #1 IMP_(P1) IMP_(S1) SF #2 EXP₁ EXP₂

When SORTD transmission is supported, the following PUCCH resourceallocation scheme can be applied. In Tables 36, 37 and 38, resources inparentheses indicate resources added to configure SORTD pairs.

TABLE 36 PCC SCC SF #1 IMP_(P1) (IMP_(P1+1)) IMP_(S1) (IMP_(S1+1)) SF #2EXP₁ (EXP₃) EXP₂ (EXP₄)

TABLE 37 PCC SCC SF #1 IMP_(P1) (EXP₃) IMP_(S1) (EXP₅) SF #2 EXP₁ (EXP₄)EXP₂ (EXP₆)

TABLE 38 PCC SCC SF #1 IMP_(P1) (IMP_(P1+1)) IMP_(S1) (EXP₄) SF #2 EXP₁(EXP₃) EXP₂ (EXP₅)

TDD RA 3) Implicit RA Only for SF #2

Only implicit PUCCH resources can be applied to SF #2 as follows.

TABLE 39 PCC SCC SF #1 EXP₁ EXP₂ SF #2 IMP_(P2) IMP_(S2)

When SORTD transmission is supported, the following PUCCH resourceallocation scheme can be applied. In Tables 40, 41 and 42, resources inparentheses indicate resources added to configure SORTD pairs.

TABLE 40 PCC SCC SF #1 EXP₁ (EXP₃) EXP₂ (EXP₄) SF #2 IMP_(P2)(IMP_(P2+1)) IMP_(S2) (IMP_(S2+1))

TABLE 41 PCC SCC SF #1 EXP₁ (EXP₃) EXP₂ (EXP₅) SF #2 IMP_(P2) (EXP₄)IMP_(S2) (EXP₆)

TABLE 42 PCC SCC SF #1 EXP₁ (EXP₃) EXP₂ (EXP₄) SF #2 IMP_(P2)(IMP_(P2+1)) IMP_(S2) (EXP₅)

TDD RA 4) Implicit RA Only for PCC

Only implicit PUCCH resources can be applied to the PCC as follows.

TABLE 43 PCC SCC SF #1 IMP_(P1) EXP₁ SF #2 IMP_(P2) EXP₂

When SORTD transmission is supported, the following PUCCH resourceallocation scheme can be applied. In Tables 44 and 45, resources inparentheses indicate resources added to configure SORTD pairs.

TABLE 44 PCC SCC SF #1 IMP_(P1) (IMP_(P1+1)) EXP₁ (EXP₃) SF #2 IMP_(P2)(IMP_(P2+1)) EXP₂ (EXP₄)

TABLE 45 PCC SCC SF #1 IMP_(P1) (EXP₃) EXP₁ (EXP₅) SF #2 IMP_(P2) (EXP₄)EXP₂ (EXP₆)

When one or more of the PCC and SCC are configured as the MIMOtransmission mode, it is possible to apply CW bundling to thecorresponding CCs and then apply the above-described TDD RAs 1 to 4thereto.

FIG. 16 illustrates a BS and a UE applicable to an embodiment of thepresent invention. When a wireless communication system includes arelay, communication is performed between a BS and the relay on abackhaul link and between the relay and a UE on an access link. The BSor UE shown in FIG. 16 can be replaced by a relay as necessary.

Referring to FIG. 16, an RF communication system includes a BS 110 and aUE 120. The BS 110 includes a processor 112, a memory 114 and an RF unit116. The processor 112 may be configured to implement the proceduresand/or methods proposed by the present invention. The memory 114 isconnected to the processor 112 and stores various types of informationrelating to operations of the processor 112. The RF unit 116 isconnected to the processor 112 and transmits and/or receives RF signals.The UE 120 includes a processor 122, a memory 124 and an RF unit 126.The processor 122 may be configured to implement the procedures and/ormethods proposed by the present invention. The memory 124 is connectedto the processor 122 and stores various types of information relating tooperations of the processor 122. The RF unit 126 is connected to theprocessor 122 and transmits and/or receives RF signals. The BS 110 andthe UE 120 may have a single antenna or multiple antennas.

The embodiments of the present invention described hereinbelow arecombinations of elements and features of the present invention. Theelements or features may be considered selective unless otherwisementioned. Each element or feature may be practiced without beingcombined with other elements or features. Further, an embodiment of thepresent invention may be constructed by combining parts of the elementsand/or features. Operation orders described in embodiments of thepresent invention may be rearranged. Some constructions of any oneembodiment may be included in another embodiment and may be replacedwith corresponding constructions of another embodiment. It is obvious tothose skilled in the art that claims that are not explicitly cited ineach other in the appended claims may be presented in combination as anembodiment of the present invention or included as a new claim by asubsequent amendment after the application is filed.

In the embodiments of the present invention, a description is made,centering on a data transmission and reception relationship between a BSand a UE. In some cases, a specific operation described as performed bythe BS may be performed by an upper node of the BS. Namely, it isapparent that, in a network comprised of a plurality of network nodesincluding a BS, various operations performed for communication with anMS may be performed by the BS, or network nodes other than the BS. Theterm ‘eNB’ may be replaced with the term ‘fixed station’, ‘Node B’,‘Base Station (BS)’, ‘access point’, etc. The term ‘UE’ may be replacedwith the term ‘Mobile Station (MS)’, ‘Mobile Subscriber Station (MSS)’,‘mobile terminal’, etc.

The embodiments of the present invention may be achieved by variousmeans, for example, hardware, firmware, software, or a combinationthereof. In a hardware configuration, the methods according to theembodiments of the present invention may be achieved by one or moreApplication Specific Integrated Circuits (ASICs), Digital SignalProcessors (DSPs), Digital Signal Processing Devices (DSPDs),Programmable Logic Devices (PLDs), Field Programmable Gate Arrays(FPGAs), processors, controllers, microcontrollers, microprocessors,etc.

In a firmware or software configuration, the embodiments of the presentinvention may be implemented in the form of a module, a procedure, afunction, etc. For example, software code may be stored in a memory unitand executed by a processor. The memory unit is located at the interioror exterior of the processor and may transmit and receive data to andfrom the processor via various known means.

Those skilled in the art will appreciate that the present invention maybe carried out in other specific ways than those set forth hereinwithout departing from the spirit and essential characteristics of thepresent invention. The above embodiments are therefore to be construedin all aspects as illustrative and not restrictive. The scope of theinvention should be determined by the appended claims and their legalequivalents, not by the above description, and all changes coming withinthe meaning and equivalency range of the appended claims are intended tobe embraced therein.

INDUSTRIAL APPLICABILITY

The present invention is applicable to wireless communicationapparatuses such as a UE, a relay, a BS, etc.

The invention claimed is:
 1. A method for receiving uplink controlinformation when a plurality of cells including a primary cell and asecondary cell are configured for a user equipment (UE) in a wirelesscommunication system, the method performed by a base station andcomprising: receiving, through multiple antennas, a bit valuecorresponding to a plurality of Hybrid Automatic Repeat reQuest(HARQ)-ACKs on a Physical Uplink Control Channel (PUCCH) resource pairwhich is selected from among a plurality of PUCCH resource pairs for aPUCCH format 1b, wherein the plurality of PUCCH resource pairs includesresources shown in the following table, PUCCH resource PUCCH PUCCH PUCCHpair #1 resource pair #2 resource pair #3 resource pair #4 TX IMP_(P)IMP_(P+1) EXP₃ EXP₅ #N TX EXP₁ EXP₂ EXP₄ EXP₆ #M

wherein TX #N and TX #M respectively denote antenna ports N and M,IMP_(P) denotes a PUCCH resource linked to a lowest Control ChannelElement (CCE) index n_(CCE,P) corresponding to a Physical DownlinkControl Channel (PDCCH) related with a Physical Downlink Shared Channel(PDSCH) in the primary cell, IMP_(P+1) represents a PUCCH resourcelinked to n_(CCE,P)+1, and wherein EXP₁, EXP₂, EXP₃, EXP₄, EXP₅, andEXP₆ represent PUCCH resources configured by a higher layer.
 2. Themethod according to claim 1, wherein the primary cell includes a primarycomponent carrier (PCC) and the secondary cell includes a secondarycomponent carrier (SCC).
 3. The method according to claim 1, wherein aPDCCH related with a PDSCH in the secondary cell is transmitted throughthe secondary cell.
 4. A base station configured to receive uplinkcontrol information when a plurality of cells including a primary celland a secondary cell are configured for a user equipment (UE) in awireless communication system, the base station comprising: an radiofrequency (RF) unit; and a processor, wherein the processor isconfigured to receive, through multiple antennas and the RF unit, a bitvalue corresponding to a plurality of Hybrid Automatic Repeat reQuest(HARQ)-ACKs on a Physical Uplink Control Channel (PUCCH) resource pairwhich is selected from among a plurality of PUCCH resource pairs for aPUCCH format 1b, wherein the plurality of PUCCH resource pairs includesresources shown in the following table, PUCCH resource PUCCH PUCCH PUCCHpair #1 resource pair #2 resource pair #3 resource pair #4 TX IMP_(P)IMP_(P+1) EXP₃ EXP₅ #N TX EXP₁ EXP₂ EXP₄ EXP₆ #M

wherein TX #N and TX #M respectively denote antenna ports N and M,IMP_(P) denotes a PUCCH resource linked to a lowest Control ChannelElement (CCE) index n_(CCE,P) corresponding to a Physical DownlinkControl Channel (PDCCH) related with a Physical Downlink Shared Channel(PDSCH) in the primary cell, IMP_(P+1) represents a PUCCH resourcelinked to n_(CCE,P)+1, and wherein EXP₁, EXP₂, EXP₃, EXP₄, EXP₅, andEXP₆ represent PUCCH resources configured by a higher layer.
 5. The basestation according to claim 4, wherein the primary cell includes aprimary component carrier (PCC) and the secondary cell includes asecondary component carrier (SCC).
 6. The base station according toclaim 4, wherein a PDCCH related with a PDSCH in the secondary cell istransmitted through the secondary cell.